[PATCH v2 0/7] Remove unused /dev/oldmem interface

[PATCH v2 0/7] Remove unused /dev/oldmem interface

[Zhang Yanfei]

/dev/oldmem provides the interface for us to access the "old memory" in
the dump-capture kernel. Unfortunately, no one actually uses this interface.

And this interface could actually cause some real problems if used on ia64
where the cached/uncached accesses are mixed. See the discussion from
the link: https://lkml.org/lkml/2013/4/12/386.

So Eric suggested that we should remove /dev/oldmem as an unused piece of
code.

Besides, we used a global variable saved_max_pfn to let the capture kernel
know the amount of memory that the previous kernel used. And for almost all
architectures (except x86. In x86, saved_max_pfn is used by detect_calgary()),
the only user of this variable is the read_oldmem interface of /dev/oldmem, so
also remove the setting for saved_max_pfn in those architectures.

-v2:
Keep /dev/oldmem and its number 12 in case this number will get reused in the
future. And mark it obsolete since /dev/oldmem will be removed from kernel.

Zhang Yanfei (7):
  /dev/oldmem: Remove this interface
  Documentation/devices.txt: Mark /dev/oldmem obsolete
  Documentation/kdump/kdump.txt: Remove /dev/oldmem description
  mips: Remove savemaxmem parameter setup
  powerpc: Remove savemaxmem parameter setup
  ia64: Remove setting for saved_max_pfn
  s390: Remove setting for saved_max_pfn

 Documentation/devices.txt        |    3 +-
 Documentation/kdump/kdump.txt    |   31 +++++--------------------
 arch/ia64/kernel/efi.c           |    5 ----
 arch/mips/kernel/crash_dump.c    |   10 --------
 arch/powerpc/kernel/crash_dump.c |   10 --------
 arch/s390/kernel/setup.c         |    4 ---
 drivers/char/mem.c               |   47 --------------------------------------
 7 files changed, 7 insertions(+), 103 deletions(-)

[PATCH v2 0/7] Remove unused /dev/oldmem interface

[Zhang Yanfei]

/dev/oldmem provides the interface for us to access the "old memory" in
the dump-capture kernel. Unfortunately, no one actually uses this interface.

And this interface could actually cause some real problems if used on ia64
where the cached/uncached accesses are mixed. See the discussion from
the link: https://lkml.org/lkml/2013/4/12/386.

So Eric suggested that we should remove /dev/oldmem as an unused piece of
code.

Besides, we used a global variable saved_max_pfn to let the capture kernel
know the amount of memory that the previous kernel used. And for almost all
architectures (except x86. In x86, saved_max_pfn is used by detect_calgary()),
the only user of this variable is the read_oldmem interface of /dev/oldmem, so
also remove the setting for saved_max_pfn in those architectures.

-v2:
Keep /dev/oldmem and its number 12 in case this number will get reused in the
future. And mark it obsolete since /dev/oldmem will be removed from kernel.

Zhang Yanfei (7):
  /dev/oldmem: Remove this interface
  Documentation/devices.txt: Mark /dev/oldmem obsolete
  Documentation/kdump/kdump.txt: Remove /dev/oldmem description
  mips: Remove savemaxmem parameter setup
  powerpc: Remove savemaxmem parameter setup
  ia64: Remove setting for saved_max_pfn
  s390: Remove setting for saved_max_pfn

 Documentation/devices.txt        |    3 +-
 Documentation/kdump/kdump.txt    |   31 +++++--------------------
 arch/ia64/kernel/efi.c           |    5 ----
 arch/mips/kernel/crash_dump.c    |   10 --------
 arch/powerpc/kernel/crash_dump.c |   10 --------
 arch/s390/kernel/setup.c         |    4 ---
 drivers/char/mem.c               |   47 --------------------------------------
 7 files changed, 7 insertions(+), 103 deletions(-)


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[PATCH v2 1/7] /dev/oldmem: Remove the interface

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

/dev/oldmem provides the interface for us to access the "old memory" in
the dump-capture kernel. Unfortunately, no one actually uses this interface.

And this interface could actually cause some real problems if used on ia64
where the cached/uncached accesses are mixed. See the discussion from
the link: https://lkml.org/lkml/2013/4/12/386.

So Eric suggested that we should remove /dev/oldmem as an unused piece of
code.

Suggested-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 drivers/char/mem.c |   47 -----------------------------------------------
 1 files changed, 0 insertions(+), 47 deletions(-)

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 1ccbe94..bbe8ab4 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -21,7 +21,6 @@
 #include <linux/ptrace.h>
 #include <linux/device.h>
 #include <linux/highmem.h>
-#include <linux/crash_dump.h>
 #include <linux/backing-dev.h>
 #include <linux/bootmem.h>
 #include <linux/splice.h>
@@ -357,40 +356,6 @@ static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
 }
 #endif
 
-#ifdef CONFIG_CRASH_DUMP
-/*
- * Read memory corresponding to the old kernel.
- */
-static ssize_t read_oldmem(struct file *file, char __user *buf,
-				size_t count, loff_t *ppos)
-{
-	unsigned long pfn, offset;
-	size_t read = 0, csize;
-	int rc = 0;
-
-	while (count) {
-		pfn = *ppos / PAGE_SIZE;
-		if (pfn > saved_max_pfn)
-			return read;
-
-		offset = (unsigned long)(*ppos % PAGE_SIZE);
-		if (count > PAGE_SIZE - offset)
-			csize = PAGE_SIZE - offset;
-		else
-			csize = count;
-
-		rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
-		if (rc < 0)
-			return rc;
-		buf += csize;
-		*ppos += csize;
-		read += csize;
-		count -= csize;
-	}
-	return read;
-}
-#endif
-
 #ifdef CONFIG_DEVKMEM
 /*
  * This function reads the *virtual* memory as seen by the kernel.
@@ -772,7 +737,6 @@ static int open_port(struct inode *inode, struct file *filp)
 #define aio_write_zero	aio_write_null
 #define open_mem	open_port
 #define open_kmem	open_mem
-#define open_oldmem	open_mem
 
 static const struct file_operations mem_fops = {
 	.llseek		= memory_lseek,
@@ -837,14 +801,6 @@ static const struct file_operations full_fops = {
 	.write		= write_full,
 };
 
-#ifdef CONFIG_CRASH_DUMP
-static const struct file_operations oldmem_fops = {
-	.read	= read_oldmem,
-	.open	= open_oldmem,
-	.llseek = default_llseek,
-};
-#endif
-
 static const struct memdev {
 	const char *name;
 	umode_t mode;
@@ -866,9 +822,6 @@ static const struct memdev {
 #ifdef CONFIG_PRINTK
 	[11] = { "kmsg", 0644, &kmsg_fops, NULL },
 #endif
-#ifdef CONFIG_CRASH_DUMP
-	[12] = { "oldmem", 0, &oldmem_fops, NULL },
-#endif
 };
 
 static int memory_open(struct inode *inode, struct file *filp)
-- 
1.7.1

[PATCH v2 1/7] /dev/oldmem: Remove the interface

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

/dev/oldmem provides the interface for us to access the "old memory" in
the dump-capture kernel. Unfortunately, no one actually uses this interface.

And this interface could actually cause some real problems if used on ia64
where the cached/uncached accesses are mixed. See the discussion from
the link: https://lkml.org/lkml/2013/4/12/386.

So Eric suggested that we should remove /dev/oldmem as an unused piece of
code.

Suggested-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Dave Hansen <dave@sr71.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
---
 drivers/char/mem.c |   47 -----------------------------------------------
 1 files changed, 0 insertions(+), 47 deletions(-)

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 1ccbe94..bbe8ab4 100644
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -21,7 +21,6 @@
 #include <linux/ptrace.h>
 #include <linux/device.h>
 #include <linux/highmem.h>
-#include <linux/crash_dump.h>
 #include <linux/backing-dev.h>
 #include <linux/bootmem.h>
 #include <linux/splice.h>
@@ -357,40 +356,6 @@ static int mmap_kmem(struct file *file, struct vm_area_struct *vma)
 }
 #endif
 
-#ifdef CONFIG_CRASH_DUMP
-/*
- * Read memory corresponding to the old kernel.
- */
-static ssize_t read_oldmem(struct file *file, char __user *buf,
-				size_t count, loff_t *ppos)
-{
-	unsigned long pfn, offset;
-	size_t read = 0, csize;
-	int rc = 0;
-
-	while (count) {
-		pfn = *ppos / PAGE_SIZE;
-		if (pfn > saved_max_pfn)
-			return read;
-
-		offset = (unsigned long)(*ppos % PAGE_SIZE);
-		if (count > PAGE_SIZE - offset)
-			csize = PAGE_SIZE - offset;
-		else
-			csize = count;
-
-		rc = copy_oldmem_page(pfn, buf, csize, offset, 1);
-		if (rc < 0)
-			return rc;
-		buf += csize;
-		*ppos += csize;
-		read += csize;
-		count -= csize;
-	}
-	return read;
-}
-#endif
-
 #ifdef CONFIG_DEVKMEM
 /*
  * This function reads the *virtual* memory as seen by the kernel.
@@ -772,7 +737,6 @@ static int open_port(struct inode *inode, struct file *filp)
 #define aio_write_zero	aio_write_null
 #define open_mem	open_port
 #define open_kmem	open_mem
-#define open_oldmem	open_mem
 
 static const struct file_operations mem_fops = {
 	.llseek		= memory_lseek,
@@ -837,14 +801,6 @@ static const struct file_operations full_fops = {
 	.write		= write_full,
 };
 
-#ifdef CONFIG_CRASH_DUMP
-static const struct file_operations oldmem_fops = {
-	.read	= read_oldmem,
-	.open	= open_oldmem,
-	.llseek = default_llseek,
-};
-#endif
-
 static const struct memdev {
 	const char *name;
 	umode_t mode;
@@ -866,9 +822,6 @@ static const struct memdev {
 #ifdef CONFIG_PRINTK
 	[11] = { "kmsg", 0644, &kmsg_fops, NULL },
 #endif
-#ifdef CONFIG_CRASH_DUMP
-	[12] = { "oldmem", 0, &oldmem_fops, NULL },
-#endif
 };
 
 static int memory_open(struct inode *inode, struct file *filp)
-- 
1.7.1


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[PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Dave Jones <davej@redhat.com>
---
 Documentation/devices.txt |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/Documentation/devices.txt b/Documentation/devices.txt
index 08f01e7..c8e4002 100644
--- a/Documentation/devices.txt
+++ b/Documentation/devices.txt
@@ -100,8 +100,7 @@ Your cooperation is appreciated.
 		 10 = /dev/aio		Asynchronous I/O notification interface
 		 11 = /dev/kmsg		Writes to this come out as printk's, reads
 					export the buffered printk records.
-		 12 = /dev/oldmem	Used by crashdump kernels to access
-					the memory of the kernel that crashed.
+		 12 = /dev/oldmem	OBSOLETE
 
   1 block	RAM disk
 		  0 = /dev/ram0		First RAM disk
-- 
1.7.1

[PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Dave Jones <davej@redhat.com>
---
 Documentation/devices.txt |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/Documentation/devices.txt b/Documentation/devices.txt
index 08f01e7..c8e4002 100644
--- a/Documentation/devices.txt
+++ b/Documentation/devices.txt
@@ -100,8 +100,7 @@ Your cooperation is appreciated.
 		 10 = /dev/aio		Asynchronous I/O notification interface
 		 11 = /dev/kmsg		Writes to this come out as printk's, reads
 					export the buffered printk records.
-		 12 = /dev/oldmem	Used by crashdump kernels to access
-					the memory of the kernel that crashed.
+		 12 = /dev/oldmem	OBSOLETE
 
   1 block	RAM disk
 		  0 = /dev/ram0		First RAM disk
-- 
1.7.1

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Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[HATAYAMA Daisuke]

(2013/05/26 15:36), Zhang Yanfei wrote:
> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>
> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> Cc: Dave Jones <davej@redhat.com>
> ---
>   Documentation/devices.txt |    3 +--
>   1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
> index 08f01e7..c8e4002 100644
> --- a/Documentation/devices.txt
> +++ b/Documentation/devices.txt
> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>   		 10 = /dev/aio		Asynchronous I/O notification interface
>   		 11 = /dev/kmsg		Writes to this come out as printk's, reads
>   					export the buffered printk records.
> -		 12 = /dev/oldmem	Used by crashdump kernels to access
> -					the memory of the kernel that crashed.
> +		 12 = /dev/oldmem	OBSOLETE
>
>     1 block	RAM disk
>   		  0 = /dev/ram0		First RAM disk
>

This is the new patch. Looking at other parts of devices.txt, obsolete is
sometimes used together with unused. I guess obsolete means this is old interface so
don't use it as much as possible and unused means this is not used at all now.
You remove old memory interface completely in this patch set, so is it better to add
unused, too?

-- 
Thanks.
HATAYAMA, Daisuke

Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[HATAYAMA Daisuke]

(2013/05/26 15:36), Zhang Yanfei wrote:
> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>
> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> Cc: Dave Jones <davej@redhat.com>
> ---
>   Documentation/devices.txt |    3 +--
>   1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
> index 08f01e7..c8e4002 100644
> --- a/Documentation/devices.txt
> +++ b/Documentation/devices.txt
> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>   		 10 = /dev/aio		Asynchronous I/O notification interface
>   		 11 = /dev/kmsg		Writes to this come out as printk's, reads
>   					export the buffered printk records.
> -		 12 = /dev/oldmem	Used by crashdump kernels to access
> -					the memory of the kernel that crashed.
> +		 12 = /dev/oldmem	OBSOLETE
>
>     1 block	RAM disk
>   		  0 = /dev/ram0		First RAM disk
>

This is the new patch. Looking at other parts of devices.txt, obsolete is
sometimes used together with unused. I guess obsolete means this is old interface so
don't use it as much as possible and unused means this is not used at all now.
You remove old memory interface completely in this patch set, so is it better to add
unused, too?

-- 
Thanks.
HATAYAMA, Daisuke


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Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Zhang Yanfei]

于 2013年05月27日 09:46, HATAYAMA Daisuke 写道:
> (2013/05/26 15:36), Zhang Yanfei wrote:
>> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>>
>> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>> Cc: Dave Jones <davej@redhat.com>
>> ---
>>   Documentation/devices.txt |    3 +--
>>   1 files changed, 1 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
>> index 08f01e7..c8e4002 100644
>> --- a/Documentation/devices.txt
>> +++ b/Documentation/devices.txt
>> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>>            10 = /dev/aio        Asynchronous I/O notification interface
>>            11 = /dev/kmsg        Writes to this come out as printk's, reads
>>                       export the buffered printk records.
>> -         12 = /dev/oldmem    Used by crashdump kernels to access
>> -                    the memory of the kernel that crashed.
>> +         12 = /dev/oldmem    OBSOLETE
>>
>>     1 block    RAM disk
>>             0 = /dev/ram0        First RAM disk
>>
> 
> This is the new patch. Looking at other parts of devices.txt, obsolete is
> sometimes used together with unused. I guess obsolete means this is old interface so
> don't use it as much as possible and unused means this is not used at all now.
> You remove old memory interface completely in this patch set, so is it better to add
> unused, too?
> 

Does obsolete also mean "not used anymore"? I don't know. I think we can wait for some native
English speakers to comment on this.

Thanks
Zhang

Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Zhang Yanfei]

于 2013年05月27日 09:46, HATAYAMA Daisuke 写道:
> (2013/05/26 15:36), Zhang Yanfei wrote:
>> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>>
>> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>> Cc: Dave Jones <davej@redhat.com>
>> ---
>>   Documentation/devices.txt |    3 +--
>>   1 files changed, 1 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
>> index 08f01e7..c8e4002 100644
>> --- a/Documentation/devices.txt
>> +++ b/Documentation/devices.txt
>> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>>            10 = /dev/aio        Asynchronous I/O notification interface
>>            11 = /dev/kmsg        Writes to this come out as printk's, reads
>>                       export the buffered printk records.
>> -         12 = /dev/oldmem    Used by crashdump kernels to access
>> -                    the memory of the kernel that crashed.
>> +         12 = /dev/oldmem    OBSOLETE
>>
>>     1 block    RAM disk
>>             0 = /dev/ram0        First RAM disk
>>
> 
> This is the new patch. Looking at other parts of devices.txt, obsolete is
> sometimes used together with unused. I guess obsolete means this is old interface so
> don't use it as much as possible and unused means this is not used at all now.
> You remove old memory interface completely in this patch set, so is it better to add
> unused, too?
> 

Does obsolete also mean "not used anymore"? I don't know. I think we can wait for some native
English speakers to comment on this.

Thanks
Zhang

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Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[HATAYAMA Daisuke]

(2013/05/27 10:54), Zhang Yanfei wrote:
> 于 2013年05月27日 09:46, HATAYAMA Daisuke 写道:
>> (2013/05/26 15:36), Zhang Yanfei wrote:
>>> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>>>
>>> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>>> Cc: Dave Jones <davej@redhat.com>
>>> ---
>>>    Documentation/devices.txt |    3 +--
>>>    1 files changed, 1 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
>>> index 08f01e7..c8e4002 100644
>>> --- a/Documentation/devices.txt
>>> +++ b/Documentation/devices.txt
>>> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>>>             10 = /dev/aio        Asynchronous I/O notification interface
>>>             11 = /dev/kmsg        Writes to this come out as printk's, reads
>>>                        export the buffered printk records.
>>> -         12 = /dev/oldmem    Used by crashdump kernels to access
>>> -                    the memory of the kernel that crashed.
>>> +         12 = /dev/oldmem    OBSOLETE
>>>
>>>      1 block    RAM disk
>>>              0 = /dev/ram0        First RAM disk
>>>
>>
>> This is the new patch. Looking at other parts of devices.txt, obsolete is
>> sometimes used together with unused. I guess obsolete means this is old interface so
>> don't use it as much as possible and unused means this is not used at all now.
>> You remove old memory interface completely in this patch set, so is it better to add
>> unused, too?
>>
>
> Does obsolete also mean "not used anymore"? I don't know. I think we can wait for some native
> English speakers to comment on this.
>

Yes. To be honest, I'm still suspecting "unused" doesn't include meaning of "removed"...

-- 
Thanks.
HATAYAMA, Daisuke

Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[HATAYAMA Daisuke]

(2013/05/27 10:54), Zhang Yanfei wrote:
> 于 2013年05月27日 09:46, HATAYAMA Daisuke 写道:
>> (2013/05/26 15:36), Zhang Yanfei wrote:
>>> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>>>
>>> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>>> Cc: Dave Jones <davej@redhat.com>
>>> ---
>>>    Documentation/devices.txt |    3 +--
>>>    1 files changed, 1 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
>>> index 08f01e7..c8e4002 100644
>>> --- a/Documentation/devices.txt
>>> +++ b/Documentation/devices.txt
>>> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>>>             10 = /dev/aio        Asynchronous I/O notification interface
>>>             11 = /dev/kmsg        Writes to this come out as printk's, reads
>>>                        export the buffered printk records.
>>> -         12 = /dev/oldmem    Used by crashdump kernels to access
>>> -                    the memory of the kernel that crashed.
>>> +         12 = /dev/oldmem    OBSOLETE
>>>
>>>      1 block    RAM disk
>>>              0 = /dev/ram0        First RAM disk
>>>
>>
>> This is the new patch. Looking at other parts of devices.txt, obsolete is
>> sometimes used together with unused. I guess obsolete means this is old interface so
>> don't use it as much as possible and unused means this is not used at all now.
>> You remove old memory interface completely in this patch set, so is it better to add
>> unused, too?
>>
>
> Does obsolete also mean "not used anymore"? I don't know. I think we can wait for some native
> English speakers to comment on this.
>

Yes. To be honest, I'm still suspecting "unused" doesn't include meaning of "removed"...

-- 
Thanks.
HATAYAMA, Daisuke


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Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Rob Landley]

On 05/26/2013 08:54:19 PM, Zhang Yanfei wrote:
> 于 2013年05月27日 09:46, HATAYAMA Daisuke 写道:
> > (2013/05/26 15:36), Zhang Yanfei wrote:
> >> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> >>
> >> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> >> Cc: Dave Jones <davej@redhat.com>
> >> ---
> >>   Documentation/devices.txt |    3 +--
> >>   1 files changed, 1 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
> >> index 08f01e7..c8e4002 100644
> >> --- a/Documentation/devices.txt
> >> +++ b/Documentation/devices.txt
> >> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
> >>            10 = /dev/aio        Asynchronous I/O notification  
> interface
> >>            11 = /dev/kmsg        Writes to this come out as  
> printk's, reads
> >>                       export the buffered printk records.
> >> -         12 = /dev/oldmem    Used by crashdump kernels to access
> >> -                    the memory of the kernel that crashed.
> >> +         12 = /dev/oldmem    OBSOLETE
> >>
> >>     1 block    RAM disk
> >>             0 = /dev/ram0        First RAM disk
> >>
> >
> > This is the new patch. Looking at other parts of devices.txt,  
> obsolete is
> > sometimes used together with unused. I guess obsolete means this is  
> old interface so
> > don't use it as much as possible and unused means this is not used  
> at all now.
> > You remove old memory interface completely in this patch set, so is  
> it better to add
> > unused, too?
> >
> 
> Does obsolete also mean "not used anymore"? I don't know. I think we  
> can wait for some native
> English speakers to comment on this.

Obsolete implies that it shouldn't be used anymore. There are  
exceptions to everything, of course...

(Unused means nothing is using it. If there's still code using it, it's  
not unused. So yeah unused would imply removed.)

Rob

Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Rob Landley]

On 05/26/2013 08:54:19 PM, Zhang Yanfei wrote:
> 于 2013年05月27日 09:46, HATAYAMA Daisuke 写道:
> > (2013/05/26 15:36), Zhang Yanfei wrote:
> >> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> >>
> >> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> >> Cc: Dave Jones <davej@redhat.com>
> >> ---
> >>   Documentation/devices.txt |    3 +--
> >>   1 files changed, 1 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
> >> index 08f01e7..c8e4002 100644
> >> --- a/Documentation/devices.txt
> >> +++ b/Documentation/devices.txt
> >> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
> >>            10 = /dev/aio        Asynchronous I/O notification  
> interface
> >>            11 = /dev/kmsg        Writes to this come out as  
> printk's, reads
> >>                       export the buffered printk records.
> >> -         12 = /dev/oldmem    Used by crashdump kernels to access
> >> -                    the memory of the kernel that crashed.
> >> +         12 = /dev/oldmem    OBSOLETE
> >>
> >>     1 block    RAM disk
> >>             0 = /dev/ram0        First RAM disk
> >>
> >
> > This is the new patch. Looking at other parts of devices.txt,  
> obsolete is
> > sometimes used together with unused. I guess obsolete means this is  
> old interface so
> > don't use it as much as possible and unused means this is not used  
> at all now.
> > You remove old memory interface completely in this patch set, so is  
> it better to add
> > unused, too?
> >
> 
> Does obsolete also mean "not used anymore"? I don't know. I think we  
> can wait for some native
> English speakers to comment on this.

Obsolete implies that it shouldn't be used anymore. There are  
exceptions to everything, of course...

(Unused means nothing is using it. If there's still code using it, it's  
not unused. So yeah unused would imply removed.)

Rob
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Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Zhang Yanfei]

On 05/28/2013 02:17 PM, Rob Landley wrote:
> On 05/26/2013 08:54:19 PM, Zhang Yanfei wrote:
>> 于 2013年05月27日 09:46, HATAYAMA Daisuke 写道:
>> > (2013/05/26 15:36), Zhang Yanfei wrote:
>> >> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>> >>
>> >> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>> >> Cc: Dave Jones <davej@redhat.com>
>> >> ---
>> >>   Documentation/devices.txt |    3 +--
>> >>   1 files changed, 1 insertions(+), 2 deletions(-)
>> >>
>> >> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
>> >> index 08f01e7..c8e4002 100644
>> >> --- a/Documentation/devices.txt
>> >> +++ b/Documentation/devices.txt
>> >> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>> >>            10 = /dev/aio        Asynchronous I/O notification interface
>> >>            11 = /dev/kmsg        Writes to this come out as printk's, reads
>> >>                       export the buffered printk records.
>> >> -         12 = /dev/oldmem    Used by crashdump kernels to access
>> >> -                    the memory of the kernel that crashed.
>> >> +         12 = /dev/oldmem    OBSOLETE
>> >>
>> >>     1 block    RAM disk
>> >>             0 = /dev/ram0        First RAM disk
>> >>
>> >
>> > This is the new patch. Looking at other parts of devices.txt, obsolete is
>> > sometimes used together with unused. I guess obsolete means this is old interface so
>> > don't use it as much as possible and unused means this is not used at all now.
>> > You remove old memory interface completely in this patch set, so is it better to add
>> > unused, too?
>> >
>>
>> Does obsolete also mean "not used anymore"? I don't know. I think we can wait for some native
>> English speakers to comment on this.
> 
> Obsolete implies that it shouldn't be used anymore. There are exceptions to everything, of course...
> 
> (Unused means nothing is using it. If there's still code using it, it's not unused. So yeah unused would imply removed.)
> 

So, could I just use UNSED to replace OBSOLETE here? Or use "OBSOLETE/UNUSED"?

-- 
Thanks.
Zhang Yanfei

Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Zhang Yanfei]

On 05/28/2013 02:17 PM, Rob Landley wrote:
> On 05/26/2013 08:54:19 PM, Zhang Yanfei wrote:
>> 于 2013年05月27日 09:46, HATAYAMA Daisuke 写道:
>> > (2013/05/26 15:36), Zhang Yanfei wrote:
>> >> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>> >>
>> >> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>> >> Cc: Dave Jones <davej@redhat.com>
>> >> ---
>> >>   Documentation/devices.txt |    3 +--
>> >>   1 files changed, 1 insertions(+), 2 deletions(-)
>> >>
>> >> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
>> >> index 08f01e7..c8e4002 100644
>> >> --- a/Documentation/devices.txt
>> >> +++ b/Documentation/devices.txt
>> >> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>> >>            10 = /dev/aio        Asynchronous I/O notification interface
>> >>            11 = /dev/kmsg        Writes to this come out as printk's, reads
>> >>                       export the buffered printk records.
>> >> -         12 = /dev/oldmem    Used by crashdump kernels to access
>> >> -                    the memory of the kernel that crashed.
>> >> +         12 = /dev/oldmem    OBSOLETE
>> >>
>> >>     1 block    RAM disk
>> >>             0 = /dev/ram0        First RAM disk
>> >>
>> >
>> > This is the new patch. Looking at other parts of devices.txt, obsolete is
>> > sometimes used together with unused. I guess obsolete means this is old interface so
>> > don't use it as much as possible and unused means this is not used at all now.
>> > You remove old memory interface completely in this patch set, so is it better to add
>> > unused, too?
>> >
>>
>> Does obsolete also mean "not used anymore"? I don't know. I think we can wait for some native
>> English speakers to comment on this.
> 
> Obsolete implies that it shouldn't be used anymore. There are exceptions to everything, of course...
> 
> (Unused means nothing is using it. If there's still code using it, it's not unused. So yeah unused would imply removed.)
> 

So, could I just use UNSED to replace OBSOLETE here? Or use "OBSOLETE/UNUSED"?

-- 
Thanks.
Zhang Yanfei

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Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Rob Landley]

On 05/28/2013 01:25:25 AM, Zhang Yanfei wrote:
> On 05/28/2013 02:17 PM, Rob Landley wrote:
> > On 05/26/2013 08:54:19 PM, Zhang Yanfei wrote:
> >> 于 2013年05月27日 09:46, HATAYAMA Daisuke 写道:
> >> > (2013/05/26 15:36), Zhang Yanfei wrote:
> >> >> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> >> >>
> >> >> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> >> >> Cc: Dave Jones <davej@redhat.com>
> >> >> ---
> >> >>   Documentation/devices.txt |    3 +--
> >> >>   1 files changed, 1 insertions(+), 2 deletions(-)
> >> >>
> >> >> diff --git a/Documentation/devices.txt  
> b/Documentation/devices.txt
> >> >> index 08f01e7..c8e4002 100644
> >> >> --- a/Documentation/devices.txt
> >> >> +++ b/Documentation/devices.txt
> >> >> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
> >> >>            10 = /dev/aio        Asynchronous I/O notification  
> interface
> >> >>            11 = /dev/kmsg        Writes to this come out as  
> printk's, reads
> >> >>                       export the buffered printk records.
> >> >> -         12 = /dev/oldmem    Used by crashdump kernels to  
> access
> >> >> -                    the memory of the kernel that crashed.
> >> >> +         12 = /dev/oldmem    OBSOLETE
> >> >>
> >> >>     1 block    RAM disk
> >> >>             0 = /dev/ram0        First RAM disk
> >> >>
> >> >
> >> > This is the new patch. Looking at other parts of devices.txt,  
> obsolete is
> >> > sometimes used together with unused. I guess obsolete means this  
> is old interface so
> >> > don't use it as much as possible and unused means this is not  
> used at all now.
> >> > You remove old memory interface completely in this patch set, so  
> is it better to add
> >> > unused, too?
> >> >
> >>
> >> Does obsolete also mean "not used anymore"? I don't know. I think  
> we can wait for some native
> >> English speakers to comment on this.
> >
> > Obsolete implies that it shouldn't be used anymore. There are  
> exceptions to everything, of course...
> >
> > (Unused means nothing is using it. If there's still code using it,  
> it's not unused. So yeah unused would imply removed.)
> >
> 
> So, could I just use UNSED to replace OBSOLETE here? Or use  
> "OBSOLETE/UNUSED"?

Obsolete is fine.

Obsolete means it was used at some point, and thus reusing it might  
confuse or conflcit with legacy software. Unused could just mean that  
we left a gap for some reason, it doesn't imply it ever was used.

Explicitly documenting "unused" is kind of silly: all the ones we  
_don't_ document are presumably unused. Obsolete carries with it a very  
mild warning about legacy software, which is presumably why we still  
bother to mention it at all instead of just removing the entry.

(Then again the point was that nothing ever used this interface in the  
first place. Personally I'd just have removed the entry...)

Rob

Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Rob Landley]

On 05/28/2013 01:25:25 AM, Zhang Yanfei wrote:
> On 05/28/2013 02:17 PM, Rob Landley wrote:
> > On 05/26/2013 08:54:19 PM, Zhang Yanfei wrote:
> >> 于 2013年05月27日 09:46, HATAYAMA Daisuke 写道:
> >> > (2013/05/26 15:36), Zhang Yanfei wrote:
> >> >> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> >> >>
> >> >> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> >> >> Cc: Dave Jones <davej@redhat.com>
> >> >> ---
> >> >>   Documentation/devices.txt |    3 +--
> >> >>   1 files changed, 1 insertions(+), 2 deletions(-)
> >> >>
> >> >> diff --git a/Documentation/devices.txt  
> b/Documentation/devices.txt
> >> >> index 08f01e7..c8e4002 100644
> >> >> --- a/Documentation/devices.txt
> >> >> +++ b/Documentation/devices.txt
> >> >> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
> >> >>            10 = /dev/aio        Asynchronous I/O notification  
> interface
> >> >>            11 = /dev/kmsg        Writes to this come out as  
> printk's, reads
> >> >>                       export the buffered printk records.
> >> >> -         12 = /dev/oldmem    Used by crashdump kernels to  
> access
> >> >> -                    the memory of the kernel that crashed.
> >> >> +         12 = /dev/oldmem    OBSOLETE
> >> >>
> >> >>     1 block    RAM disk
> >> >>             0 = /dev/ram0        First RAM disk
> >> >>
> >> >
> >> > This is the new patch. Looking at other parts of devices.txt,  
> obsolete is
> >> > sometimes used together with unused. I guess obsolete means this  
> is old interface so
> >> > don't use it as much as possible and unused means this is not  
> used at all now.
> >> > You remove old memory interface completely in this patch set, so  
> is it better to add
> >> > unused, too?
> >> >
> >>
> >> Does obsolete also mean "not used anymore"? I don't know. I think  
> we can wait for some native
> >> English speakers to comment on this.
> >
> > Obsolete implies that it shouldn't be used anymore. There are  
> exceptions to everything, of course...
> >
> > (Unused means nothing is using it. If there's still code using it,  
> it's not unused. So yeah unused would imply removed.)
> >
> 
> So, could I just use UNSED to replace OBSOLETE here? Or use  
> "OBSOLETE/UNUSED"?

Obsolete is fine.

Obsolete means it was used at some point, and thus reusing it might  
confuse or conflcit with legacy software. Unused could just mean that  
we left a gap for some reason, it doesn't imply it ever was used.

Explicitly documenting "unused" is kind of silly: all the ones we  
_don't_ document are presumably unused. Obsolete carries with it a very  
mild warning about legacy software, which is presumably why we still  
bother to mention it at all instead of just removing the entry.

(Then again the point was that nothing ever used this interface in the  
first place. Personally I'd just have removed the entry...)

Rob
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Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[H. Peter Anvin]

On 05/28/2013 10:26 AM, Rob Landley wrote:
>>
>> So, could I just use UNSED to replace OBSOLETE here? Or use
>> "OBSOLETE/UNUSED"?
> 
> Obsolete is fine.
> 
> Obsolete means it was used at some point, and thus reusing it might
> confuse or conflcit with legacy software. Unused could just mean that we
> left a gap for some reason, it doesn't imply it ever was used.
> 
> Explicitly documenting "unused" is kind of silly: all the ones we
> _don't_ document are presumably unused. Obsolete carries with it a very
> mild warning about legacy software, which is presumably why we still
> bother to mention it at all instead of just removing the entry.
> 
> (Then again the point was that nothing ever used this interface in the
> first place. Personally I'd just have removed the entry...)
> 

"Obsolete" in this specific context means that the reservation is
obsolete, but was used in kernels past, therefore the name and number
should not be reused to prevent old software from misbehaving.

	-hpa

Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[H. Peter Anvin]

On 05/28/2013 10:26 AM, Rob Landley wrote:
>>
>> So, could I just use UNSED to replace OBSOLETE here? Or use
>> "OBSOLETE/UNUSED"?
> 
> Obsolete is fine.
> 
> Obsolete means it was used at some point, and thus reusing it might
> confuse or conflcit with legacy software. Unused could just mean that we
> left a gap for some reason, it doesn't imply it ever was used.
> 
> Explicitly documenting "unused" is kind of silly: all the ones we
> _don't_ document are presumably unused. Obsolete carries with it a very
> mild warning about legacy software, which is presumably why we still
> bother to mention it at all instead of just removing the entry.
> 
> (Then again the point was that nothing ever used this interface in the
> first place. Personally I'd just have removed the entry...)
> 

"Obsolete" in this specific context means that the reservation is
obsolete, but was used in kernels past, therefore the name and number
should not be reused to prevent old software from misbehaving.

	-hpa



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Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Eric W. Biederman]

Zhang Yanfei <zhangyanfei.yes@gmail.com> writes:

> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>
> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> Cc: Dave Jones <davej@redhat.com>
> ---
>  Documentation/devices.txt |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
> index 08f01e7..c8e4002 100644
> --- a/Documentation/devices.txt
> +++ b/Documentation/devices.txt
> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>  		 10 = /dev/aio		Asynchronous I/O notification interface
>  		 11 = /dev/kmsg		Writes to this come out as printk's, reads
>  					export the buffered printk records.
> -		 12 = /dev/oldmem	Used by crashdump kernels to access
> -					the memory of the kernel that crashed.
> +		 12 = /dev/oldmem	OBSOLETE

Let me suggest the slightly better.

 +		12 = /dev/oldmem	OBSOLETE - replaced by /proc/vmcore

Pointing to people to /proc/vmcore should help anyone who is trying to
understand what is going on.

>    1 block	RAM disk
>  		  0 = /dev/ram0		First RAM disk

Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Eric W. Biederman]

Zhang Yanfei <zhangyanfei.yes@gmail.com> writes:

> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>
> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
> Cc: Dave Jones <davej@redhat.com>
> ---
>  Documentation/devices.txt |    3 +--
>  1 files changed, 1 insertions(+), 2 deletions(-)
>
> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
> index 08f01e7..c8e4002 100644
> --- a/Documentation/devices.txt
> +++ b/Documentation/devices.txt
> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>  		 10 = /dev/aio		Asynchronous I/O notification interface
>  		 11 = /dev/kmsg		Writes to this come out as printk's, reads
>  					export the buffered printk records.
> -		 12 = /dev/oldmem	Used by crashdump kernels to access
> -					the memory of the kernel that crashed.
> +		 12 = /dev/oldmem	OBSOLETE

Let me suggest the slightly better.

 +		12 = /dev/oldmem	OBSOLETE - replaced by /proc/vmcore

Pointing to people to /proc/vmcore should help anyone who is trying to
understand what is going on.

>    1 block	RAM disk
>  		  0 = /dev/ram0		First RAM disk

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Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Zhang Yanfei]

On 05/29/2013 06:29 AM, Eric W. Biederman wrote:
> Zhang Yanfei <zhangyanfei.yes@gmail.com> writes:
> 
>> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>>
>> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>> Cc: Dave Jones <davej@redhat.com>
>> ---
>>  Documentation/devices.txt |    3 +--
>>  1 files changed, 1 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
>> index 08f01e7..c8e4002 100644
>> --- a/Documentation/devices.txt
>> +++ b/Documentation/devices.txt
>> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>>  		 10 = /dev/aio		Asynchronous I/O notification interface
>>  		 11 = /dev/kmsg		Writes to this come out as printk's, reads
>>  					export the buffered printk records.
>> -		 12 = /dev/oldmem	Used by crashdump kernels to access
>> -					the memory of the kernel that crashed.
>> +		 12 = /dev/oldmem	OBSOLETE
> 
> Let me suggest the slightly better.
> 
>  +		12 = /dev/oldmem	OBSOLETE - replaced by /proc/vmcore
> 
> Pointing to people to /proc/vmcore should help anyone who is trying to
> understand what is going on.

Makes sense to me. Updated patch below:

-----------------------------------
>From d2f7baf2aba86069f941f32669a22dbd99082614 Mon Sep 17 00:00:00 2001
From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Date: Wed, 29 May 2013 15:44:09 +0800
Subject: [PATCH] Documentation/devices.txt: Mark /dev/oldmem obsolete

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
---
 Documentation/devices.txt |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/Documentation/devices.txt b/Documentation/devices.txt
index 08f01e7..315455a 100644
--- a/Documentation/devices.txt
+++ b/Documentation/devices.txt
@@ -100,8 +100,7 @@ Your cooperation is appreciated.
 		 10 = /dev/aio		Asynchronous I/O notification interface
 		 11 = /dev/kmsg		Writes to this come out as printk's, reads
 					export the buffered printk records.
-		 12 = /dev/oldmem	Used by crashdump kernels to access
-					the memory of the kernel that crashed.
+		 12 = /dev/oldmem	OBSOLETE - replaced by /proc/vmcore
 
   1 block	RAM disk
 		  0 = /dev/ram0		First RAM disk
-- 
1.7.1

Re: [PATCH v2 2/7] Documentation/devices.txt: Mark /dev/oldmem obsolete

[Zhang Yanfei]

On 05/29/2013 06:29 AM, Eric W. Biederman wrote:
> Zhang Yanfei <zhangyanfei.yes@gmail.com> writes:
> 
>> From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>>
>> Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
>> Cc: Dave Jones <davej@redhat.com>
>> ---
>>  Documentation/devices.txt |    3 +--
>>  1 files changed, 1 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/devices.txt b/Documentation/devices.txt
>> index 08f01e7..c8e4002 100644
>> --- a/Documentation/devices.txt
>> +++ b/Documentation/devices.txt
>> @@ -100,8 +100,7 @@ Your cooperation is appreciated.
>>  		 10 = /dev/aio		Asynchronous I/O notification interface
>>  		 11 = /dev/kmsg		Writes to this come out as printk's, reads
>>  					export the buffered printk records.
>> -		 12 = /dev/oldmem	Used by crashdump kernels to access
>> -					the memory of the kernel that crashed.
>> +		 12 = /dev/oldmem	OBSOLETE
> 
> Let me suggest the slightly better.
> 
>  +		12 = /dev/oldmem	OBSOLETE - replaced by /proc/vmcore
> 
> Pointing to people to /proc/vmcore should help anyone who is trying to
> understand what is going on.

Makes sense to me. Updated patch below:

-----------------------------------
From d2f7baf2aba86069f941f32669a22dbd99082614 Mon Sep 17 00:00:00 2001
From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Date: Wed, 29 May 2013 15:44:09 +0800
Subject: [PATCH] Documentation/devices.txt: Mark /dev/oldmem obsolete

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
---
 Documentation/devices.txt |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/Documentation/devices.txt b/Documentation/devices.txt
index 08f01e7..315455a 100644
--- a/Documentation/devices.txt
+++ b/Documentation/devices.txt
@@ -100,8 +100,7 @@ Your cooperation is appreciated.
 		 10 = /dev/aio		Asynchronous I/O notification interface
 		 11 = /dev/kmsg		Writes to this come out as printk's, reads
 					export the buffered printk records.
-		 12 = /dev/oldmem	Used by crashdump kernels to access
-					the memory of the kernel that crashed.
+		 12 = /dev/oldmem	OBSOLETE - replaced by /proc/vmcore
 
   1 block	RAM disk
 		  0 = /dev/ram0		First RAM disk
-- 
1.7.1


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[PATCH v2 3/7] Documentation/kdump/kdump.txt: Remove /dev/oldmem description

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
---
 Documentation/kdump/kdump.txt |   31 ++++++-------------------------
 1 files changed, 6 insertions(+), 25 deletions(-)

diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 9c7fd98..bec123e 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -47,19 +47,12 @@ parameter. Optionally the size of the ELF header can also be passed
 when using the elfcorehdr=[size[KMG]@]offset[KMG] syntax.
 
 
-With the dump-capture kernel, you can access the memory image, or "old
-memory," in two ways:
-
-- Through a /dev/oldmem device interface. A capture utility can read the
-  device file and write out the memory in raw format. This is a raw dump
-  of memory. Analysis and capture tools must be intelligent enough to
-  determine where to look for the right information.
-
-- Through /proc/vmcore. This exports the dump as an ELF-format file that
-  you can write out using file copy commands such as cp or scp. Further,
-  you can use analysis tools such as the GNU Debugger (GDB) and the Crash
-  tool to debug the dump file. This method ensures that the dump pages are
-  correctly ordered.
+With the dump-capture kernel, you can access the memory image through
+/proc/vmcore. This exports the dump as an ELF-format file that you can
+write out using file copy commands such as cp or scp. Further, you can
+use analysis tools such as the GNU Debugger (GDB) and the Crash tool to
+debug the dump file. This method ensures that the dump pages are correctly
+ordered.
 
 
 Setup and Installation
@@ -423,18 +416,6 @@ the following command:
 
    cp /proc/vmcore <dump-file>
 
-You can also access dumped memory as a /dev/oldmem device for a linear
-and raw view. To create the device, use the following command:
-
-    mknod /dev/oldmem c 1 12
-
-Use the dd command with suitable options for count, bs, and skip to
-access specific portions of the dump.
-
-To see the entire memory, use the following command:
-
-   dd if=/dev/oldmem of=oldmem.001
-
 
 Analysis
 ========
-- 
1.7.1

[PATCH v2 3/7] Documentation/kdump/kdump.txt: Remove /dev/oldmem description

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
---
 Documentation/kdump/kdump.txt |   31 ++++++-------------------------
 1 files changed, 6 insertions(+), 25 deletions(-)

diff --git a/Documentation/kdump/kdump.txt b/Documentation/kdump/kdump.txt
index 9c7fd98..bec123e 100644
--- a/Documentation/kdump/kdump.txt
+++ b/Documentation/kdump/kdump.txt
@@ -47,19 +47,12 @@ parameter. Optionally the size of the ELF header can also be passed
 when using the elfcorehdr=[size[KMG]@]offset[KMG] syntax.
 
 
-With the dump-capture kernel, you can access the memory image, or "old
-memory," in two ways:
-
-- Through a /dev/oldmem device interface. A capture utility can read the
-  device file and write out the memory in raw format. This is a raw dump
-  of memory. Analysis and capture tools must be intelligent enough to
-  determine where to look for the right information.
-
-- Through /proc/vmcore. This exports the dump as an ELF-format file that
-  you can write out using file copy commands such as cp or scp. Further,
-  you can use analysis tools such as the GNU Debugger (GDB) and the Crash
-  tool to debug the dump file. This method ensures that the dump pages are
-  correctly ordered.
+With the dump-capture kernel, you can access the memory image through
+/proc/vmcore. This exports the dump as an ELF-format file that you can
+write out using file copy commands such as cp or scp. Further, you can
+use analysis tools such as the GNU Debugger (GDB) and the Crash tool to
+debug the dump file. This method ensures that the dump pages are correctly
+ordered.
 
 
 Setup and Installation
@@ -423,18 +416,6 @@ the following command:
 
    cp /proc/vmcore <dump-file>
 
-You can also access dumped memory as a /dev/oldmem device for a linear
-and raw view. To create the device, use the following command:
-
-    mknod /dev/oldmem c 1 12
-
-Use the dd command with suitable options for count, bs, and skip to
-access specific portions of the dump.
-
-To see the entire memory, use the following command:
-
-   dd if=/dev/oldmem of=oldmem.001
-
 
 Analysis
 ========
-- 
1.7.1

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[PATCH v2 4/7] mips: Remove savemaxmem parameter setup

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

saved_max_pfn is used to know the amount of memory that the previous
kernel used. And for powerpc, we set saved_max_pfn by passing the
kernel commandline parameter "savemaxmem=".

The only user of saved_max_pfn in mips is read_oldmem interface.
Since we have removed read_oldmem, so we don't need this parameter
anymore.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
---
 arch/mips/kernel/crash_dump.c |   10 ----------
 1 files changed, 0 insertions(+), 10 deletions(-)

diff --git a/arch/mips/kernel/crash_dump.c b/arch/mips/kernel/crash_dump.c
index 3be9e7b..f291cf9 100644
--- a/arch/mips/kernel/crash_dump.c
+++ b/arch/mips/kernel/crash_dump.c
@@ -4,16 +4,6 @@
 #include <asm/uaccess.h>
 #include <linux/slab.h>
 
-static int __init parse_savemaxmem(char *p)
-{
-	if (p)
-		saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
-
-	return 1;
-}
-__setup("savemaxmem=", parse_savemaxmem);
-
-
 static void *kdump_buf_page;
 
 /**
-- 
1.7.1

[PATCH v2 4/7] mips: Remove savemaxmem parameter setup

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

saved_max_pfn is used to know the amount of memory that the previous
kernel used. And for powerpc, we set saved_max_pfn by passing the
kernel commandline parameter "savemaxmem=".

The only user of saved_max_pfn in mips is read_oldmem interface.
Since we have removed read_oldmem, so we don't need this parameter
anymore.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ralf Baechle <ralf@linux-mips.org>
---
 arch/mips/kernel/crash_dump.c |   10 ----------
 1 files changed, 0 insertions(+), 10 deletions(-)

diff --git a/arch/mips/kernel/crash_dump.c b/arch/mips/kernel/crash_dump.c
index 3be9e7b..f291cf9 100644
--- a/arch/mips/kernel/crash_dump.c
+++ b/arch/mips/kernel/crash_dump.c
@@ -4,16 +4,6 @@
 #include <asm/uaccess.h>
 #include <linux/slab.h>
 
-static int __init parse_savemaxmem(char *p)
-{
-	if (p)
-		saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
-
-	return 1;
-}
-__setup("savemaxmem=", parse_savemaxmem);
-
-
 static void *kdump_buf_page;
 
 /**
-- 
1.7.1


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[PATCH v2 5/7] powerpc: Remove savemaxmem parameter setup

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

saved_max_pfn is used to know the amount of memory that the previous
kernel used. And for powerpc, we set saved_max_pfn by passing the
kernel commandline parameter "savemaxmem=".

The only user of saved_max_pfn in powerpc is read_oldmem interface.
Since we have removed read_oldmem, we don't need this parameter anymore.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/kernel/crash_dump.c |   10 ----------
 1 files changed, 0 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
index 9ec3fe1..779a78c 100644
--- a/arch/powerpc/kernel/crash_dump.c
+++ b/arch/powerpc/kernel/crash_dump.c
@@ -69,16 +69,6 @@ void __init setup_kdump_trampoline(void)
 }
 #endif /* CONFIG_NONSTATIC_KERNEL */
 
-static int __init parse_savemaxmem(char *p)
-{
-	if (p)
-		saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
-
-	return 1;
-}
-__setup("savemaxmem=", parse_savemaxmem);
-
-
 static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
                                unsigned long offset, int userbuf)
 {
-- 
1.7.1

[PATCH v2 5/7] powerpc: Remove savemaxmem parameter setup

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

saved_max_pfn is used to know the amount of memory that the previous
kernel used. And for powerpc, we set saved_max_pfn by passing the
kernel commandline parameter "savemaxmem=".

The only user of saved_max_pfn in powerpc is read_oldmem interface.
Since we have removed read_oldmem, we don't need this parameter anymore.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
---
 arch/powerpc/kernel/crash_dump.c |   10 ----------
 1 files changed, 0 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/kernel/crash_dump.c b/arch/powerpc/kernel/crash_dump.c
index 9ec3fe1..779a78c 100644
--- a/arch/powerpc/kernel/crash_dump.c
+++ b/arch/powerpc/kernel/crash_dump.c
@@ -69,16 +69,6 @@ void __init setup_kdump_trampoline(void)
 }
 #endif /* CONFIG_NONSTATIC_KERNEL */
 
-static int __init parse_savemaxmem(char *p)
-{
-	if (p)
-		saved_max_pfn = (memparse(p, &p) >> PAGE_SHIFT) - 1;
-
-	return 1;
-}
-__setup("savemaxmem=", parse_savemaxmem);
-
-
 static size_t copy_oldmem_vaddr(void *vaddr, char *buf, size_t csize,
                                unsigned long offset, int userbuf)
 {
-- 
1.7.1


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[PATCH v2 6/7] ia64: Remove setting for saved_max_pfn

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

The only user of saved_max_pfn in ia64 is read_oldmem interface but we
have removed that interface, so saved_max_pfn is now unneeded in ia64,
and we needn't set it anymore.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
---
 arch/ia64/kernel/efi.c |    5 -----
 1 files changed, 0 insertions(+), 5 deletions(-)

diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c
index f034563..51bce59 100644
--- a/arch/ia64/kernel/efi.c
+++ b/arch/ia64/kernel/efi.c
@@ -1116,11 +1116,6 @@ efi_memmap_init(u64 *s, u64 *e)
 		if (!is_memory_available(md))
 			continue;
 
-#ifdef CONFIG_CRASH_DUMP
-		/* saved_max_pfn should ignore max_addr= command line arg */
-		if (saved_max_pfn < (efi_md_end(md) >> PAGE_SHIFT))
-			saved_max_pfn = (efi_md_end(md) >> PAGE_SHIFT);
-#endif
 		/*
 		 * Round ends inward to granule boundaries
 		 * Give trimmings to uncached allocator
-- 
1.7.1

[PATCH v2 6/7] ia64: Remove setting for saved_max_pfn

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

The only user of saved_max_pfn in ia64 is read_oldmem interface but we
have removed that interface, so saved_max_pfn is now unneeded in ia64,
and we needn't set it anymore.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Matt Fleming <matt.fleming@intel.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
---
 arch/ia64/kernel/efi.c |    5 -----
 1 files changed, 0 insertions(+), 5 deletions(-)

diff --git a/arch/ia64/kernel/efi.c b/arch/ia64/kernel/efi.c
index f034563..51bce59 100644
--- a/arch/ia64/kernel/efi.c
+++ b/arch/ia64/kernel/efi.c
@@ -1116,11 +1116,6 @@ efi_memmap_init(u64 *s, u64 *e)
 		if (!is_memory_available(md))
 			continue;
 
-#ifdef CONFIG_CRASH_DUMP
-		/* saved_max_pfn should ignore max_addr= command line arg */
-		if (saved_max_pfn < (efi_md_end(md) >> PAGE_SHIFT))
-			saved_max_pfn = (efi_md_end(md) >> PAGE_SHIFT);
-#endif
 		/*
 		 * Round ends inward to granule boundaries
 		 * Give trimmings to uncached allocator
-- 
1.7.1


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[PATCH v2 7/7] s390: Remove setting for saved_max_pfn

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

The only user of saved_max_pfn in s390 is read_oldmem interface but we
have removed that interface, so saved_max_pfn is now unneeded in s390,
and we needn't set it anymore.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
---
 arch/s390/kernel/setup.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 0a49095..497451e 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -719,10 +719,6 @@ static void reserve_oldmem(void)
 	}
 	create_mem_hole(memory_chunk, OLDMEM_BASE, OLDMEM_SIZE);
 	create_mem_hole(memory_chunk, OLDMEM_SIZE, real_size - OLDMEM_SIZE);
-	if (OLDMEM_BASE + OLDMEM_SIZE == real_size)
-		saved_max_pfn = PFN_DOWN(OLDMEM_BASE) - 1;
-	else
-		saved_max_pfn = PFN_DOWN(real_size) - 1;
 #endif
 }
 
-- 
1.7.1

[PATCH v2 7/7] s390: Remove setting for saved_max_pfn

[Zhang Yanfei]

From: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>

The only user of saved_max_pfn in s390 is read_oldmem interface but we
have removed that interface, so saved_max_pfn is now unneeded in s390,
and we needn't set it anymore.

Signed-off-by: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Michael Holzheu <holzheu@linux.vnet.ibm.com>
---
 arch/s390/kernel/setup.c |    4 ----
 1 files changed, 0 insertions(+), 4 deletions(-)

diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index 0a49095..497451e 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -719,10 +719,6 @@ static void reserve_oldmem(void)
 	}
 	create_mem_hole(memory_chunk, OLDMEM_BASE, OLDMEM_SIZE);
 	create_mem_hole(memory_chunk, OLDMEM_SIZE, real_size - OLDMEM_SIZE);
-	if (OLDMEM_BASE + OLDMEM_SIZE == real_size)
-		saved_max_pfn = PFN_DOWN(OLDMEM_BASE) - 1;
-	else
-		saved_max_pfn = PFN_DOWN(real_size) - 1;
 #endif
 }
 
-- 
1.7.1


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