* [PATCH] x86/earlyprintk: setup earlyprintk as early as possible
@ 2015-04-06 13:17 Alexander Kuleshov
2015-04-07 9:52 ` Ingo Molnar
0 siblings, 1 reply; 8+ messages in thread
From: Alexander Kuleshov @ 2015-04-06 13:17 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Greg Kroah-Hartman
Cc: linux-kernel, Alexander Kuleshov
As setup_earlyprintk passed to the early_param, it will be usable only after
'parse_early_param' function will be called from the 'setup_arch'. So we have
earlyprintk during early boot and decompression. Next point after decompression
of the kernel where we can use early_printk is after call of the
'parse_early_param'.
This patch removes 'earlyprintk' from the early_param and setup it right after
boot data copying. So 'early_printk' function will be usabable after
decompression of kernel and before parse_early_param will be called.
Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
---
arch/x86/kernel/early_printk.c | 4 +---
arch/x86/kernel/head64.c | 1 +
include/linux/printk.h | 1 +
3 files changed, 3 insertions(+), 3 deletions(-)
diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index a62536a..4b0577b 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -329,7 +329,7 @@ static inline void early_console_register(struct console *con, int keep_early)
register_console(early_console);
}
-static int __init setup_early_printk(char *buf)
+int __init setup_early_printk(char *buf)
{
int keep;
@@ -390,5 +390,3 @@ static int __init setup_early_printk(char *buf)
}
return 0;
}
-
-early_param("earlyprintk", setup_early_printk);
diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
index c4f8d46..0141de7 100644
--- a/arch/x86/kernel/head64.c
+++ b/arch/x86/kernel/head64.c
@@ -171,6 +171,7 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
load_idt((const struct desc_ptr *)&idt_descr);
copy_bootdata(__va(real_mode_data));
+ setup_early_printk(boot_command_line);
/*
* Load microcode early on BSP.
diff --git a/include/linux/printk.h b/include/linux/printk.h
index baa3f97..47e3919 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -115,6 +115,7 @@ int no_printk(const char *fmt, ...)
#ifdef CONFIG_EARLY_PRINTK
extern asmlinkage __printf(1, 2)
void early_printk(const char *fmt, ...);
+int setup_early_printk(char *buf);
#else
static inline __printf(1, 2) __cold
void early_printk(const char *s, ...) { }
--
2.3.3.611.g09038fc.dirty
^ permalink raw reply related [flat|nested] 8+ messages in thread
* Re: [PATCH] x86/earlyprintk: setup earlyprintk as early as possible
2015-04-06 13:17 [PATCH] x86/earlyprintk: setup earlyprintk as early as possible Alexander Kuleshov
@ 2015-04-07 9:52 ` Ingo Molnar
2015-04-07 10:19 ` Alexander Kuleshov
0 siblings, 1 reply; 8+ messages in thread
From: Ingo Molnar @ 2015-04-07 9:52 UTC (permalink / raw)
To: Alexander Kuleshov
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Greg Kroah-Hartman,
linux-kernel
* Alexander Kuleshov <kuleshovmail@gmail.com> wrote:
> As setup_earlyprintk passed to the early_param, it will be usable only after
> 'parse_early_param' function will be called from the 'setup_arch'. So we have
> earlyprintk during early boot and decompression. Next point after decompression
> of the kernel where we can use early_printk is after call of the
> 'parse_early_param'.
>
> This patch removes 'earlyprintk' from the early_param and setup it right after
> boot data copying. So 'early_printk' function will be usabable after
> decompression of kernel and before parse_early_param will be called.
>
> Signed-off-by: Alexander Kuleshov <kuleshovmail@gmail.com>
> ---
> arch/x86/kernel/early_printk.c | 4 +---
> arch/x86/kernel/head64.c | 1 +
> include/linux/printk.h | 1 +
> 3 files changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
> index a62536a..4b0577b 100644
> --- a/arch/x86/kernel/early_printk.c
> +++ b/arch/x86/kernel/early_printk.c
> @@ -329,7 +329,7 @@ static inline void early_console_register(struct console *con, int keep_early)
> register_console(early_console);
> }
>
> -static int __init setup_early_printk(char *buf)
> +int __init setup_early_printk(char *buf)
> {
> int keep;
>
> @@ -390,5 +390,3 @@ static int __init setup_early_printk(char *buf)
> }
> return 0;
> }
> -
> -early_param("earlyprintk", setup_early_printk);
> diff --git a/arch/x86/kernel/head64.c b/arch/x86/kernel/head64.c
> index c4f8d46..0141de7 100644
> --- a/arch/x86/kernel/head64.c
> +++ b/arch/x86/kernel/head64.c
> @@ -171,6 +171,7 @@ asmlinkage __visible void __init x86_64_start_kernel(char * real_mode_data)
> load_idt((const struct desc_ptr *)&idt_descr);
>
> copy_bootdata(__va(real_mode_data));
> + setup_early_printk(boot_command_line);
>
> /*
> * Load microcode early on BSP.
> diff --git a/include/linux/printk.h b/include/linux/printk.h
> index baa3f97..47e3919 100644
> --- a/include/linux/printk.h
> +++ b/include/linux/printk.h
> @@ -115,6 +115,7 @@ int no_printk(const char *fmt, ...)
> #ifdef CONFIG_EARLY_PRINTK
> extern asmlinkage __printf(1, 2)
> void early_printk(const char *fmt, ...);
> +int setup_early_printk(char *buf);
> #else
> static inline __printf(1, 2) __cold
> void early_printk(const char *s, ...) { }
This looks useful.
It would be nice to test it via a well placed printk() and check that
before the patch the message doesn't go to the serial console and
after the patch the message indeed arrives on the early serial console
- or something like that.
Thanks,
Ingo
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] x86/earlyprintk: setup earlyprintk as early as possible
2015-04-07 9:52 ` Ingo Molnar
@ 2015-04-07 10:19 ` Alexander Kuleshov
2015-04-07 10:24 ` Ingo Molnar
0 siblings, 1 reply; 8+ messages in thread
From: Alexander Kuleshov @ 2015-04-07 10:19 UTC (permalink / raw)
To: Ingo Molnar
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Greg Kroah-Hartman, LKML
2015-04-07 15:52 GMT+06:00 Ingo Molnar <mingo@kernel.org>:
>
> It would be nice to test it via a well placed printk() and check that
> before the patch the message doesn't go to the serial console and
> after the patch the message indeed arrives on the early serial console
> - or something like that.
I have tested this patch when i wrote it and early_printk does not print
anything before the parse_early_param. But i don't know how to show this
in code in a correct way. Maybe we should to give back early_printk call
which i removed in the previous patch
(https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=91d8f0416f3989e248d3a3d3efb821eda10a85d2)?
Any one another question about this. I submited patch only for head64.c
and it does not affect kernel for i386, because i'm not sure where is
the best place to setup earlyprintk in the head32.c. I thought to put
it in the start of i386_start_kernel(void) (from head32.c) but not sure
about it.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] x86/earlyprintk: setup earlyprintk as early as possible
2015-04-07 10:19 ` Alexander Kuleshov
@ 2015-04-07 10:24 ` Ingo Molnar
2015-04-07 10:31 ` Alexander Kuleshov
0 siblings, 1 reply; 8+ messages in thread
From: Ingo Molnar @ 2015-04-07 10:24 UTC (permalink / raw)
To: Alexander Kuleshov
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Greg Kroah-Hartman, LKML
* Alexander Kuleshov <kuleshovmail@gmail.com> wrote:
> 2015-04-07 15:52 GMT+06:00 Ingo Molnar <mingo@kernel.org>:
> >
> > It would be nice to test it via a well placed printk() and check that
> > before the patch the message doesn't go to the serial console and
> > after the patch the message indeed arrives on the early serial console
> > - or something like that.
>
> I have tested this patch when i wrote it and early_printk does not print
> anything before the parse_early_param. But i don't know how to show this
> in code in a correct way. [...]
Just add a debug printk() for your own testing, right after the param
initialization call, to be confident that the early console indeed
works.
> which i removed in the previous patch
> (https://git.kernel.org/cgit/linux/kernel/git/next/linux-next.git/commit/?id=91d8f0416f3989e248d3a3d3efb821eda10a85d2)?
>
> Any one another question about this. I submited patch only for
> head64.c and it does not affect kernel for i386, because i'm not
> sure where is the best place to setup earlyprintk in the head32.c. I
> thought to put it in the start of i386_start_kernel(void) (from
> head32.c) but not sure about it.
I'd use i386_start_kernel() on 32-bit and x86_64_start_kernel() on
64-bit - but I haven't tested whether it actually works.
Thanks,
Ingo
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] x86/earlyprintk: setup earlyprintk as early as possible
2015-04-07 10:24 ` Ingo Molnar
@ 2015-04-07 10:31 ` Alexander Kuleshov
2015-04-07 10:33 ` Ingo Molnar
2015-04-07 19:07 ` Yinghai Lu
0 siblings, 2 replies; 8+ messages in thread
From: Alexander Kuleshov @ 2015-04-07 10:31 UTC (permalink / raw)
To: Ingo Molnar
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Greg Kroah-Hartman, LKML
> Ingo Molnar <mingo@kernel.org>: wrote:
>
> Just add a debug printk() for your own testing, right after the param
> initialization call, to be confident that the early console indeed
> works.
>
I already tested it as you said when was writing this patch and it works.
>
> I'd use i386_start_kernel() on 32-bit and x86_64_start_kernel() on
> 64-bit - but I haven't tested whether it actually works.
>
As i already wrote, i tested it for x86_64 and it works. I will put earlyprintk
setup in the start of the i386_start_kernel, will test it with 32-bit
and resend two
patches if they will be good.
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] x86/earlyprintk: setup earlyprintk as early as possible
2015-04-07 10:31 ` Alexander Kuleshov
@ 2015-04-07 10:33 ` Ingo Molnar
2015-04-07 19:07 ` Yinghai Lu
1 sibling, 0 replies; 8+ messages in thread
From: Ingo Molnar @ 2015-04-07 10:33 UTC (permalink / raw)
To: Alexander Kuleshov
Cc: Thomas Gleixner, Ingo Molnar, H. Peter Anvin, Greg Kroah-Hartman, LKML
* Alexander Kuleshov <kuleshovmail@gmail.com> wrote:
> > Ingo Molnar <mingo@kernel.org>: wrote:
> >
> > Just add a debug printk() for your own testing, right after the param
> > initialization call, to be confident that the early console indeed
> > works.
> >
>
> I already tested it as you said when was writing this patch and it works.
The changelog does not tell us this and it should.
Thanks,
Ingo
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] x86/earlyprintk: setup earlyprintk as early as possible
2015-04-07 10:31 ` Alexander Kuleshov
2015-04-07 10:33 ` Ingo Molnar
@ 2015-04-07 19:07 ` Yinghai Lu
2015-04-07 19:08 ` Yinghai Lu
1 sibling, 1 reply; 8+ messages in thread
From: Yinghai Lu @ 2015-04-07 19:07 UTC (permalink / raw)
To: Alexander Kuleshov
Cc: Ingo Molnar, Thomas Gleixner, Ingo Molnar, H. Peter Anvin,
Greg Kroah-Hartman, LKML
[-- Attachment #1: Type: text/plain, Size: 684 bytes --]
On Tue, Apr 7, 2015 at 3:31 AM, Alexander Kuleshov
<kuleshovmail@gmail.com> wrote:
>
> As i already wrote, i tested it for x86_64 and it works. I will put earlyprintk
> setup in the start of the i386_start_kernel, will test it with 32-bit
> and resend two
> patches if they will be good.
No, that is not enough.
early_printk would handle not only serial console with io port accessing.
You need to make sure all other path including pciserial/dbgp/efi is safe.
They are using early_ioremap, and you can not call early_ioremap()
before early_ioremap.
otherwise you may need to just search "serial string in boot command line" like
i did in moving earlycon early patch.
Yinghai
[-- Attachment #2: setup_early_console_x1_pa_symbol_before_earlcon.patch --]
[-- Type: text/x-patch, Size: 4256 bytes --]
Subject: [PATCH -v5] x86: Setup early console as early as possible in x86_start_kernel()
Analyze "console=uart8250,io,0x3f8,115200n8" in i386_start_kernel/x86_64_start_kernel,
and call setup_early_serial8250_console() to init early serial console.
Only can handle io port kind of 8250, because mmio need ioremap.
Use boot_params.hdr.version instead of adding another variable, Suggested by hpa.
Also need to apply this one after x86 memblock patchset.
-v5: fix check when console string is last one in command line.
should use strchrnul(,' ') instead strchr(,' ') for end searching.
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
---
arch/x86/include/asm/setup.h | 2 ++
arch/x86/kernel/head.c | 26 ++++++++++++++++++++++++++
arch/x86/kernel/head32.c | 1 +
arch/x86/kernel/head64.c | 5 ++++-
kernel/printk/printk.c | 11 +++++++----
5 files changed, 40 insertions(+), 5 deletions(-)
Index: linux-2.6/arch/x86/include/asm/setup.h
===================================================================
--- linux-2.6.orig/arch/x86/include/asm/setup.h
+++ linux-2.6/arch/x86/include/asm/setup.h
@@ -40,6 +40,8 @@ static inline void vsmp_init(void) { }
void setup_bios_corruption_check(void);
extern unsigned long saved_video_mode;
+int setup_early_serial8250_console(char *cmdline);
+void setup_early_console(void);
extern void reserve_standard_io_resources(void);
extern void i386_reserve_resources(void);
Index: linux-2.6/arch/x86/kernel/head.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/head.c
+++ linux-2.6/arch/x86/kernel/head.c
@@ -69,3 +69,29 @@ void __init reserve_ebda_region(void)
/* reserve all memory between lowmem and the 1MB mark */
memblock_reserve(lowmem, 0x100000 - lowmem);
}
+
+void __init setup_early_console(void)
+{
+#ifdef CONFIG_SERIAL_8250_CONSOLE
+ char constr[64], *p, *q;
+
+ /* Can not handle mmio type 8250 uart yet, too early */
+ p = strstr(boot_command_line, "console=uart8250,io,");
+ if (!p)
+ p = strstr(boot_command_line, "console=uart,io,");
+ if (!p)
+ return;
+
+ p += 8; /* sizeof "console=" */
+ q = strchrnul(p, ' ');
+ if ((q - p) >= sizeof(constr))
+ return;
+
+ memset(constr, 0, sizeof(constr));
+ memcpy(constr, p, q - p);
+
+ lockdep_init();
+
+ setup_early_serial8250_console(constr);
+#endif
+}
Index: linux-2.6/arch/x86/kernel/head32.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/head32.c
+++ linux-2.6/arch/x86/kernel/head32.c
@@ -33,6 +33,7 @@ asmlinkage __visible void __init i386_st
{
cr4_init_shadow();
sanitize_boot_params(&boot_params);
+ setup_early_console();
/* Call the subarch specific early setup function */
switch (boot_params.hdr.hardware_subarch) {
Index: linux-2.6/arch/x86/kernel/head64.c
===================================================================
--- linux-2.6.orig/arch/x86/kernel/head64.c
+++ linux-2.6/arch/x86/kernel/head64.c
@@ -171,6 +171,7 @@ asmlinkage __visible void __init x86_64_
load_idt((const struct desc_ptr *)&idt_descr);
copy_bootdata(__va(real_mode_data));
+ setup_early_console();
/*
* Load microcode early on BSP.
@@ -192,8 +193,10 @@ asmlinkage __visible void __init x86_64_
void __init x86_64_start_reservations(char *real_mode_data)
{
/* version is always not zero if it is copied */
- if (!boot_params.hdr.version)
+ if (!boot_params.hdr.version) {
copy_bootdata(__va(real_mode_data));
+ setup_early_console();
+ }
reserve_ebda_region();
Index: linux-2.6/kernel/printk/printk.c
===================================================================
--- linux-2.6.orig/kernel/printk/printk.c
+++ linux-2.6/kernel/printk/printk.c
@@ -2409,11 +2409,14 @@ void register_console(struct console *ne
struct console_cmdline *c;
if (console_drivers)
- for_each_console(bcon)
- if (WARN(bcon == newcon,
- "console '%s%d' already registered\n",
- bcon->name, bcon->index))
+ for_each_console(bcon) {
+ /* not again */
+ if (bcon == newcon) {
+ printk(KERN_INFO "console '%s%d' already registered\n",
+ bcon->name, bcon->index);
return;
+ }
+ }
/*
* before we register a new CON_BOOT console, make sure we don't
^ permalink raw reply [flat|nested] 8+ messages in thread
* Re: [PATCH] x86/earlyprintk: setup earlyprintk as early as possible
2015-04-07 19:07 ` Yinghai Lu
@ 2015-04-07 19:08 ` Yinghai Lu
0 siblings, 0 replies; 8+ messages in thread
From: Yinghai Lu @ 2015-04-07 19:08 UTC (permalink / raw)
To: Alexander Kuleshov
Cc: Ingo Molnar, Thomas Gleixner, Ingo Molnar, H. Peter Anvin,
Greg Kroah-Hartman, LKML
On Tue, Apr 7, 2015 at 12:07 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> On Tue, Apr 7, 2015 at 3:31 AM, Alexander Kuleshov
> <kuleshovmail@gmail.com> wrote:
>
>>
>> As i already wrote, i tested it for x86_64 and it works. I will put earlyprintk
>> setup in the start of the i386_start_kernel, will test it with 32-bit
>> and resend two
>> patches if they will be good.
>
> No, that is not enough.
> early_printk would handle not only serial console with io port accessing.
> You need to make sure all other path including pciserial/dbgp/efi is safe.
> They are using early_ioremap, and you can not call early_ioremap()
> before early_ioremap.
They are using early_ioremap, and you can not call early_ioremap()
before early_ioremap_init.
>
> otherwise you may need to just search "serial string in boot command line" like
> i did in moving earlycon early patch.
>
> Yinghai
^ permalink raw reply [flat|nested] 8+ messages in thread
end of thread, other threads:[~2015-04-07 19:08 UTC | newest]
Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
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2015-04-06 13:17 [PATCH] x86/earlyprintk: setup earlyprintk as early as possible Alexander Kuleshov
2015-04-07 9:52 ` Ingo Molnar
2015-04-07 10:19 ` Alexander Kuleshov
2015-04-07 10:24 ` Ingo Molnar
2015-04-07 10:31 ` Alexander Kuleshov
2015-04-07 10:33 ` Ingo Molnar
2015-04-07 19:07 ` Yinghai Lu
2015-04-07 19:08 ` Yinghai Lu
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