* [PATCH -next] Documentation: Improve crashkernel= description @ 2011-02-06 15:41 ` Ahmed S. Darwish 0 siblings, 0 replies; 25+ messages in thread From: Ahmed S. Darwish @ 2011-02-06 15:41 UTC (permalink / raw) To: Randy Dunlap, Vivek Goyal, Haren Myneni Cc: Eric Biederman, kexec, LKML, linux-doc (Also applicable over 2.6.38-rc3) Had to explore two C code files to make sense of the 'crashkernel=' kernel parameter values. Improve the situation. Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> --- diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 89835a4..8f26b42 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] - crashkernel=nn[KMG]@ss[KMG] - [KNL] Reserve a chunk of physical memory to - hold a kernel to switch to with kexec on panic. + crashkernel=size[KMG][@offset[KMG]] + [KNL] Using kexec, Linux can switch to a 'crash kernel' + upon panic. This parameter reserves the physical + memory region [offset, offset + size] for that kernel + image. If the '@offset' part was ignored, Linux finds + a suitable crash image start address automatically. crashkernel=range1:size1[,range2:size2,...][@offset] [KNL] Same as above, but depends on the memory regards, -- Darwish http://darwish.07.googlepages.com ^ permalink raw reply related [flat|nested] 25+ messages in thread
* [PATCH -next] Documentation: Improve crashkernel= description @ 2011-02-06 15:41 ` Ahmed S. Darwish 0 siblings, 0 replies; 25+ messages in thread From: Ahmed S. Darwish @ 2011-02-06 15:41 UTC (permalink / raw) To: Randy Dunlap, Vivek Goyal, Haren Myneni Cc: linux-doc, kexec, Eric Biederman, LKML (Also applicable over 2.6.38-rc3) Had to explore two C code files to make sense of the 'crashkernel=' kernel parameter values. Improve the situation. Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> --- diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 89835a4..8f26b42 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] - crashkernel=nn[KMG]@ss[KMG] - [KNL] Reserve a chunk of physical memory to - hold a kernel to switch to with kexec on panic. + crashkernel=size[KMG][@offset[KMG]] + [KNL] Using kexec, Linux can switch to a 'crash kernel' + upon panic. This parameter reserves the physical + memory region [offset, offset + size] for that kernel + image. If the '@offset' part was ignored, Linux finds + a suitable crash image start address automatically. crashkernel=range1:size1[,range2:size2,...][@offset] [KNL] Same as above, but depends on the memory regards, -- Darwish http://darwish.07.googlepages.com _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply related [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description 2011-02-06 15:41 ` Ahmed S. Darwish @ 2011-02-06 21:57 ` Simon Horman -1 siblings, 0 replies; 25+ messages in thread From: Simon Horman @ 2011-02-06 21:57 UTC (permalink / raw) To: Ahmed S. Darwish Cc: Randy Dunlap, Vivek Goyal, Haren Myneni, Eric Biederman, kexec, LKML, linux-doc On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: > (Also applicable over 2.6.38-rc3) > > Had to explore two C code files to make sense of the 'crashkernel=' > kernel parameter values. Improve the situation. > > Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > --- > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 89835a4..8f26b42 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > Format: > <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > - crashkernel=nn[KMG]@ss[KMG] > - [KNL] Reserve a chunk of physical memory to > - hold a kernel to switch to with kexec on panic. > + crashkernel=size[KMG][@offset[KMG]] > + [KNL] Using kexec, Linux can switch to a 'crash kernel' > + upon panic. This parameter reserves the physical > + memory region [offset, offset + size] for that kernel > + image. If the '@offset' part was ignored, Linux finds > + a suitable crash image start address automatically. I think this would be further improved as: ... If '@offset' is omitted then a suitable offset is selected automatically. > > crashkernel=range1:size1[,range2:size2,...][@offset] > [KNL] Same as above, but depends on the memory > > regards, > > -- > Darwish > http://darwish.07.googlepages.com > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description @ 2011-02-06 21:57 ` Simon Horman 0 siblings, 0 replies; 25+ messages in thread From: Simon Horman @ 2011-02-06 21:57 UTC (permalink / raw) To: Ahmed S. Darwish Cc: linux-doc, kexec, LKML, Haren Myneni, Randy Dunlap, Eric Biederman, Vivek Goyal On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: > (Also applicable over 2.6.38-rc3) > > Had to explore two C code files to make sense of the 'crashkernel=' > kernel parameter values. Improve the situation. > > Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > --- > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 89835a4..8f26b42 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > Format: > <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > - crashkernel=nn[KMG]@ss[KMG] > - [KNL] Reserve a chunk of physical memory to > - hold a kernel to switch to with kexec on panic. > + crashkernel=size[KMG][@offset[KMG]] > + [KNL] Using kexec, Linux can switch to a 'crash kernel' > + upon panic. This parameter reserves the physical > + memory region [offset, offset + size] for that kernel > + image. If the '@offset' part was ignored, Linux finds > + a suitable crash image start address automatically. I think this would be further improved as: ... If '@offset' is omitted then a suitable offset is selected automatically. > > crashkernel=range1:size1[,range2:size2,...][@offset] > [KNL] Same as above, but depends on the memory > > regards, > > -- > Darwish > http://darwish.07.googlepages.com > -- > To unsubscribe from this list: send the line "unsubscribe linux-kernel" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html > Please read the FAQ at http://www.tux.org/lkml/ > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description 2011-02-06 21:57 ` Simon Horman @ 2011-02-07 2:25 ` Rob Landley -1 siblings, 0 replies; 25+ messages in thread From: Rob Landley @ 2011-02-07 2:25 UTC (permalink / raw) To: Simon Horman Cc: Ahmed S. Darwish, Randy Dunlap, Vivek Goyal, Haren Myneni, Eric Biederman, kexec, LKML, linux-doc On 02/06/2011 03:57 PM, Simon Horman wrote: > On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: >> (Also applicable over 2.6.38-rc3) >> >> Had to explore two C code files to make sense of the 'crashkernel=' >> kernel parameter values. Improve the situation. >> >> Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> >> --- >> >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt >> index 89835a4..8f26b42 100644 >> --- a/Documentation/kernel-parameters.txt >> +++ b/Documentation/kernel-parameters.txt >> @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file >> Format: >> <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] >> >> - crashkernel=nn[KMG]@ss[KMG] >> - [KNL] Reserve a chunk of physical memory to >> - hold a kernel to switch to with kexec on panic. >> + crashkernel=size[KMG][@offset[KMG]] >> + [KNL] Using kexec, Linux can switch to a 'crash kernel' >> + upon panic. This parameter reserves the physical >> + memory region [offset, offset + size] for that kernel >> + image. If the '@offset' part was ignored, Linux finds >> + a suitable crash image start address automatically. > > I think this would be further improved as: > > ... If '@offset' is omitted then a suitable > offset is selected automatically. Suitable offset as in parses a known image type (ELF, bzImage, etc) to find the start address? Or just assumes the entry point and load address are the same? Is this the size for just the kernel image, or also for the physical memory it uses so it won't overwrite the existing kernel's stuff on the way up? (If a compressed kernel wants to decompress itself or extract an initramfs for itself, what happens?) Rob ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description @ 2011-02-07 2:25 ` Rob Landley 0 siblings, 0 replies; 25+ messages in thread From: Rob Landley @ 2011-02-07 2:25 UTC (permalink / raw) To: Simon Horman Cc: linux-doc, kexec, LKML, Ahmed S. Darwish, Haren Myneni, Randy Dunlap, Eric Biederman, Vivek Goyal On 02/06/2011 03:57 PM, Simon Horman wrote: > On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: >> (Also applicable over 2.6.38-rc3) >> >> Had to explore two C code files to make sense of the 'crashkernel=' >> kernel parameter values. Improve the situation. >> >> Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> >> --- >> >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt >> index 89835a4..8f26b42 100644 >> --- a/Documentation/kernel-parameters.txt >> +++ b/Documentation/kernel-parameters.txt >> @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file >> Format: >> <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] >> >> - crashkernel=nn[KMG]@ss[KMG] >> - [KNL] Reserve a chunk of physical memory to >> - hold a kernel to switch to with kexec on panic. >> + crashkernel=size[KMG][@offset[KMG]] >> + [KNL] Using kexec, Linux can switch to a 'crash kernel' >> + upon panic. This parameter reserves the physical >> + memory region [offset, offset + size] for that kernel >> + image. If the '@offset' part was ignored, Linux finds >> + a suitable crash image start address automatically. > > I think this would be further improved as: > > ... If '@offset' is omitted then a suitable > offset is selected automatically. Suitable offset as in parses a known image type (ELF, bzImage, etc) to find the start address? Or just assumes the entry point and load address are the same? Is this the size for just the kernel image, or also for the physical memory it uses so it won't overwrite the existing kernel's stuff on the way up? (If a compressed kernel wants to decompress itself or extract an initramfs for itself, what happens?) Rob _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description 2011-02-07 2:25 ` Rob Landley @ 2011-02-07 2:35 ` Eric W. Biederman -1 siblings, 0 replies; 25+ messages in thread From: Eric W. Biederman @ 2011-02-07 2:35 UTC (permalink / raw) To: Rob Landley Cc: Simon Horman, Ahmed S. Darwish, Randy Dunlap, Vivek Goyal, Haren Myneni, kexec, LKML, linux-doc Rob Landley <rlandley@parallels.com> writes: 2> On 02/06/2011 03:57 PM, Simon Horman wrote: >> On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: >>> (Also applicable over 2.6.38-rc3) >>> >>> Had to explore two C code files to make sense of the 'crashkernel=' >>> kernel parameter values. Improve the situation. >>> >>> Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> >>> --- >>> >>> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt >>> index 89835a4..8f26b42 100644 >>> --- a/Documentation/kernel-parameters.txt >>> +++ b/Documentation/kernel-parameters.txt >>> @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file >>> Format: >>> <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] >>> >>> - crashkernel=nn[KMG]@ss[KMG] >>> - [KNL] Reserve a chunk of physical memory to >>> - hold a kernel to switch to with kexec on panic. >>> + crashkernel=size[KMG][@offset[KMG]] >>> + [KNL] Using kexec, Linux can switch to a 'crash kernel' >>> + upon panic. This parameter reserves the physical >>> + memory region [offset, offset + size] for that kernel >>> + image. If the '@offset' part was ignored, Linux finds >>> + a suitable crash image start address automatically. >> >> I think this would be further improved as: >> >> ... If '@offset' is omitted then a suitable >> offset is selected automatically. > > Suitable offset as in parses a known image type (ELF, bzImage, etc) to > find the start address? Or just assumes the entry point and load > address are the same? Neither. Suitable as in an offset that is naturally aligned for the size up to I think 16MB where the kernel doesn't care anymore. Saying that somewhere would be good but I don't think the definition of suitable belongs in a reference doc like kernel-parameters.txt The important things for users is to know that they don't need to specify offset anymore. > Is this the size for just the kernel image, or also for the physical > memory it uses so it won't overwrite the existing kernel's stuff on the > way up? (If a compressed kernel wants to decompress itself or extract > an initramfs for itself, what happens?) The size is the size of the area reserved for the crash capture kernel to run in. The crash capture kernel never uses anything else. All of the parsing etc is done in user space via /sbin/kexec. Eric ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description @ 2011-02-07 2:35 ` Eric W. Biederman 0 siblings, 0 replies; 25+ messages in thread From: Eric W. Biederman @ 2011-02-07 2:35 UTC (permalink / raw) To: Rob Landley Cc: linux-doc, kexec, LKML, Ahmed S. Darwish, Haren Myneni, Randy Dunlap, Simon Horman, Vivek Goyal Rob Landley <rlandley@parallels.com> writes: 2> On 02/06/2011 03:57 PM, Simon Horman wrote: >> On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: >>> (Also applicable over 2.6.38-rc3) >>> >>> Had to explore two C code files to make sense of the 'crashkernel=' >>> kernel parameter values. Improve the situation. >>> >>> Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> >>> --- >>> >>> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt >>> index 89835a4..8f26b42 100644 >>> --- a/Documentation/kernel-parameters.txt >>> +++ b/Documentation/kernel-parameters.txt >>> @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file >>> Format: >>> <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] >>> >>> - crashkernel=nn[KMG]@ss[KMG] >>> - [KNL] Reserve a chunk of physical memory to >>> - hold a kernel to switch to with kexec on panic. >>> + crashkernel=size[KMG][@offset[KMG]] >>> + [KNL] Using kexec, Linux can switch to a 'crash kernel' >>> + upon panic. This parameter reserves the physical >>> + memory region [offset, offset + size] for that kernel >>> + image. If the '@offset' part was ignored, Linux finds >>> + a suitable crash image start address automatically. >> >> I think this would be further improved as: >> >> ... If '@offset' is omitted then a suitable >> offset is selected automatically. > > Suitable offset as in parses a known image type (ELF, bzImage, etc) to > find the start address? Or just assumes the entry point and load > address are the same? Neither. Suitable as in an offset that is naturally aligned for the size up to I think 16MB where the kernel doesn't care anymore. Saying that somewhere would be good but I don't think the definition of suitable belongs in a reference doc like kernel-parameters.txt The important things for users is to know that they don't need to specify offset anymore. > Is this the size for just the kernel image, or also for the physical > memory it uses so it won't overwrite the existing kernel's stuff on the > way up? (If a compressed kernel wants to decompress itself or extract > an initramfs for itself, what happens?) The size is the size of the area reserved for the crash capture kernel to run in. The crash capture kernel never uses anything else. All of the parsing etc is done in user space via /sbin/kexec. Eric _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description 2011-02-07 2:25 ` Rob Landley @ 2011-02-07 2:42 ` Simon Horman -1 siblings, 0 replies; 25+ messages in thread From: Simon Horman @ 2011-02-07 2:42 UTC (permalink / raw) To: Rob Landley Cc: linux-doc, kexec, LKML, Ahmed S. Darwish, Haren Myneni, Randy Dunlap, Eric Biederman, Vivek Goyal On Sun, Feb 06, 2011 at 08:25:20PM -0600, Rob Landley wrote: > On 02/06/2011 03:57 PM, Simon Horman wrote: > > On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: > >> (Also applicable over 2.6.38-rc3) > >> > >> Had to explore two C code files to make sense of the 'crashkernel=' > >> kernel parameter values. Improve the situation. > >> > >> Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > >> --- > >> > >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > >> index 89835a4..8f26b42 100644 > >> --- a/Documentation/kernel-parameters.txt > >> +++ b/Documentation/kernel-parameters.txt > >> @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > >> Format: > >> <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > >> > >> - crashkernel=nn[KMG]@ss[KMG] > >> - [KNL] Reserve a chunk of physical memory to > >> - hold a kernel to switch to with kexec on panic. > >> + crashkernel=size[KMG][@offset[KMG]] > >> + [KNL] Using kexec, Linux can switch to a 'crash kernel' > >> + upon panic. This parameter reserves the physical > >> + memory region [offset, offset + size] for that kernel > >> + image. If the '@offset' part was ignored, Linux finds > >> + a suitable crash image start address automatically. > > > > I think this would be further improved as: > > > > ... If '@offset' is omitted then a suitable > > offset is selected automatically. > > Suitable offset as in parses a known image type (ELF, bzImage, etc) to > find the start address? Or just assumes the entry point and load > address are the same? As in it finds a large enough area of contiguous free memory. I believe that originally it searched from the bottom of memory, it may be slightly smarter now. Suitable is perhaps too strong a term. In terms of the start address. On x86 at least it used to be important to make sure that the start address matched but these days using a relocatable kernel is an easier option. > Is this the size for just the kernel image, or also for the physical > memory it uses so it won't overwrite the existing kernel's stuff on the > way up? (If a compressed kernel wants to decompress itself or extract > an initramfs for itself, what happens?) It is the memory that is used by the crash-kernel to avoid overwriting the first-kernel's stuff. It is not the memory where the (usually compressed) second-kernel is stored before it is kexeced. If a compressed crash-kernel wants to decompress itself it does so in the available memory which is the region reserved by the crash-kernel parameter to the first-kernel. ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description @ 2011-02-07 2:42 ` Simon Horman 0 siblings, 0 replies; 25+ messages in thread From: Simon Horman @ 2011-02-07 2:42 UTC (permalink / raw) To: Rob Landley Cc: linux-doc, kexec, LKML, Ahmed S. Darwish, Haren Myneni, Randy Dunlap, Eric Biederman, Vivek Goyal On Sun, Feb 06, 2011 at 08:25:20PM -0600, Rob Landley wrote: > On 02/06/2011 03:57 PM, Simon Horman wrote: > > On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: > >> (Also applicable over 2.6.38-rc3) > >> > >> Had to explore two C code files to make sense of the 'crashkernel=' > >> kernel parameter values. Improve the situation. > >> > >> Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > >> --- > >> > >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > >> index 89835a4..8f26b42 100644 > >> --- a/Documentation/kernel-parameters.txt > >> +++ b/Documentation/kernel-parameters.txt > >> @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > >> Format: > >> <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > >> > >> - crashkernel=nn[KMG]@ss[KMG] > >> - [KNL] Reserve a chunk of physical memory to > >> - hold a kernel to switch to with kexec on panic. > >> + crashkernel=size[KMG][@offset[KMG]] > >> + [KNL] Using kexec, Linux can switch to a 'crash kernel' > >> + upon panic. This parameter reserves the physical > >> + memory region [offset, offset + size] for that kernel > >> + image. If the '@offset' part was ignored, Linux finds > >> + a suitable crash image start address automatically. > > > > I think this would be further improved as: > > > > ... If '@offset' is omitted then a suitable > > offset is selected automatically. > > Suitable offset as in parses a known image type (ELF, bzImage, etc) to > find the start address? Or just assumes the entry point and load > address are the same? As in it finds a large enough area of contiguous free memory. I believe that originally it searched from the bottom of memory, it may be slightly smarter now. Suitable is perhaps too strong a term. In terms of the start address. On x86 at least it used to be important to make sure that the start address matched but these days using a relocatable kernel is an easier option. > Is this the size for just the kernel image, or also for the physical > memory it uses so it won't overwrite the existing kernel's stuff on the > way up? (If a compressed kernel wants to decompress itself or extract > an initramfs for itself, what happens?) It is the memory that is used by the crash-kernel to avoid overwriting the first-kernel's stuff. It is not the memory where the (usually compressed) second-kernel is stored before it is kexeced. If a compressed crash-kernel wants to decompress itself it does so in the available memory which is the region reserved by the crash-kernel parameter to the first-kernel. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description 2011-02-07 2:42 ` Simon Horman @ 2011-02-07 14:33 ` Vivek Goyal -1 siblings, 0 replies; 25+ messages in thread From: Vivek Goyal @ 2011-02-07 14:33 UTC (permalink / raw) To: Simon Horman Cc: Rob Landley, linux-doc, kexec, LKML, Ahmed S. Darwish, Haren Myneni, Randy Dunlap, Eric Biederman, H. Peter Anvin On Mon, Feb 07, 2011 at 11:42:38AM +0900, Simon Horman wrote: > On Sun, Feb 06, 2011 at 08:25:20PM -0600, Rob Landley wrote: > > On 02/06/2011 03:57 PM, Simon Horman wrote: > > > On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: > > >> (Also applicable over 2.6.38-rc3) > > >> > > >> Had to explore two C code files to make sense of the 'crashkernel=' > > >> kernel parameter values. Improve the situation. > > >> > > >> Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > > >> --- > > >> > > >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > > >> index 89835a4..8f26b42 100644 > > >> --- a/Documentation/kernel-parameters.txt > > >> +++ b/Documentation/kernel-parameters.txt > > >> @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > > >> Format: > > >> <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > >> > > >> - crashkernel=nn[KMG]@ss[KMG] > > >> - [KNL] Reserve a chunk of physical memory to > > >> - hold a kernel to switch to with kexec on panic. > > >> + crashkernel=size[KMG][@offset[KMG]] > > >> + [KNL] Using kexec, Linux can switch to a 'crash kernel' > > >> + upon panic. This parameter reserves the physical > > >> + memory region [offset, offset + size] for that kernel > > >> + image. If the '@offset' part was ignored, Linux finds > > >> + a suitable crash image start address automatically. > > > > > > I think this would be further improved as: > > > > > > ... If '@offset' is omitted then a suitable > > > offset is selected automatically. > > > > Suitable offset as in parses a known image type (ELF, bzImage, etc) to > > find the start address? Or just assumes the entry point and load > > address are the same? > > As in it finds a large enough area of contiguous free memory. > I believe that originally it searched from the bottom of memory, > it may be slightly smarter now. Now it has been changed to search from top of the memory (atleast for x86) and that caused few troubles. On 32bit it searches for memory under 512MB and on x86_64, it searches for memory under 896MB. Though hpa had suggested to enhance the command line syntax such that a user specifies the upper bound on memory. Something like crashkernel=x < y. So reserve X amount of memory below y MB. It boils down to same thing that somebody has to know that what is the maximum physical memory locaton kernel can boot from. I think it is dependent on kernel as well as dependent on kexec-tools. I am wondering if it is possible to make this info part of bzImage protocol where kernel tells bootloader the maximum physical memory kernel can be loaded at. I think this is off topic in the context of this patch, just a thought... Thanks Vivek ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description @ 2011-02-07 14:33 ` Vivek Goyal 0 siblings, 0 replies; 25+ messages in thread From: Vivek Goyal @ 2011-02-07 14:33 UTC (permalink / raw) To: Simon Horman Cc: linux-doc, Rob Landley, kexec, LKML, Ahmed S. Darwish, Haren Myneni, Randy Dunlap, Eric Biederman, H. Peter Anvin On Mon, Feb 07, 2011 at 11:42:38AM +0900, Simon Horman wrote: > On Sun, Feb 06, 2011 at 08:25:20PM -0600, Rob Landley wrote: > > On 02/06/2011 03:57 PM, Simon Horman wrote: > > > On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: > > >> (Also applicable over 2.6.38-rc3) > > >> > > >> Had to explore two C code files to make sense of the 'crashkernel=' > > >> kernel parameter values. Improve the situation. > > >> > > >> Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > > >> --- > > >> > > >> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > > >> index 89835a4..8f26b42 100644 > > >> --- a/Documentation/kernel-parameters.txt > > >> +++ b/Documentation/kernel-parameters.txt > > >> @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > > >> Format: > > >> <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > >> > > >> - crashkernel=nn[KMG]@ss[KMG] > > >> - [KNL] Reserve a chunk of physical memory to > > >> - hold a kernel to switch to with kexec on panic. > > >> + crashkernel=size[KMG][@offset[KMG]] > > >> + [KNL] Using kexec, Linux can switch to a 'crash kernel' > > >> + upon panic. This parameter reserves the physical > > >> + memory region [offset, offset + size] for that kernel > > >> + image. If the '@offset' part was ignored, Linux finds > > >> + a suitable crash image start address automatically. > > > > > > I think this would be further improved as: > > > > > > ... If '@offset' is omitted then a suitable > > > offset is selected automatically. > > > > Suitable offset as in parses a known image type (ELF, bzImage, etc) to > > find the start address? Or just assumes the entry point and load > > address are the same? > > As in it finds a large enough area of contiguous free memory. > I believe that originally it searched from the bottom of memory, > it may be slightly smarter now. Now it has been changed to search from top of the memory (atleast for x86) and that caused few troubles. On 32bit it searches for memory under 512MB and on x86_64, it searches for memory under 896MB. Though hpa had suggested to enhance the command line syntax such that a user specifies the upper bound on memory. Something like crashkernel=x < y. So reserve X amount of memory below y MB. It boils down to same thing that somebody has to know that what is the maximum physical memory locaton kernel can boot from. I think it is dependent on kernel as well as dependent on kexec-tools. I am wondering if it is possible to make this info part of bzImage protocol where kernel tells bootloader the maximum physical memory kernel can be loaded at. I think this is off topic in the context of this patch, just a thought... Thanks Vivek _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description 2011-02-07 2:25 ` Rob Landley ` (2 preceding siblings ...) (?) @ 2011-02-07 10:59 ` WANG Cong -1 siblings, 0 replies; 25+ messages in thread From: WANG Cong @ 2011-02-07 10:59 UTC (permalink / raw) To: kexec; +Cc: linux-kernel, linux-doc On Sun, 06 Feb 2011 20:25:20 -0600, Rob Landley wrote: > > Suitable offset as in parses a known image type (ELF, bzImage, etc) to > find the start address? Or just assumes the entry point and load > address are the same? No, that is the start physical address of crashkernel, which should be your system RAM not reserved by your BIOS etc.. The beginning of the physical memory is often fragmented, thus specifying a fixed offset may not work on a specific machine. > > Is this the size for just the kernel image, or also for the physical > memory it uses so it won't overwrite the existing kernel's stuff on the > way up? (If a compressed kernel wants to decompress itself or extract > an initramfs for itself, what happens?) > The size means the whole physical memory size available to the second kernel (i.e. crash kernel), which includes the memory occupied by vmlinuz, initrd, *and* the memory which will be used by the programs inside initrd (e.g. /sbin/init). If this memory is not sufficient, you will get OOM. _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description 2011-02-06 21:57 ` Simon Horman @ 2011-02-07 4:14 ` Randy Dunlap -1 siblings, 0 replies; 25+ messages in thread From: Randy Dunlap @ 2011-02-07 4:14 UTC (permalink / raw) To: Simon Horman Cc: Ahmed S. Darwish, Vivek Goyal, Haren Myneni, Eric Biederman, kexec, LKML, linux-doc On Mon, 7 Feb 2011 06:57:33 +0900 Simon Horman wrote: > On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: > > (Also applicable over 2.6.38-rc3) > > > > Had to explore two C code files to make sense of the 'crashkernel=' > > kernel parameter values. Improve the situation. > > > > Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > > --- > > > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > > index 89835a4..8f26b42 100644 > > --- a/Documentation/kernel-parameters.txt > > +++ b/Documentation/kernel-parameters.txt > > @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > > Format: > > <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > > > - crashkernel=nn[KMG]@ss[KMG] > > - [KNL] Reserve a chunk of physical memory to > > - hold a kernel to switch to with kexec on panic. > > + crashkernel=size[KMG][@offset[KMG]] > > + [KNL] Using kexec, Linux can switch to a 'crash kernel' > > + upon panic. This parameter reserves the physical > > + memory region [offset, offset + size] for that kernel > > + image. If the '@offset' part was ignored, Linux finds > > + a suitable crash image start address automatically. > > I think this would be further improved as: > > ... If '@offset' is omitted then a suitable > offset is selected automatically. > > > > > crashkernel=range1:size1[,range2:size2,...][@offset] > > [KNL] Same as above, but depends on the memory Hi, I also prefer Simon's change. Can you please resend an updated patch? thanks, --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH -next] Documentation: Improve crashkernel= description @ 2011-02-07 4:14 ` Randy Dunlap 0 siblings, 0 replies; 25+ messages in thread From: Randy Dunlap @ 2011-02-07 4:14 UTC (permalink / raw) To: Simon Horman Cc: linux-doc, kexec, LKML, Ahmed S. Darwish, Haren Myneni, Eric Biederman, Vivek Goyal On Mon, 7 Feb 2011 06:57:33 +0900 Simon Horman wrote: > On Sun, Feb 06, 2011 at 05:41:08PM +0200, Ahmed S. Darwish wrote: > > (Also applicable over 2.6.38-rc3) > > > > Had to explore two C code files to make sense of the 'crashkernel=' > > kernel parameter values. Improve the situation. > > > > Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > > --- > > > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > > index 89835a4..8f26b42 100644 > > --- a/Documentation/kernel-parameters.txt > > +++ b/Documentation/kernel-parameters.txt > > @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > > Format: > > <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > > > - crashkernel=nn[KMG]@ss[KMG] > > - [KNL] Reserve a chunk of physical memory to > > - hold a kernel to switch to with kexec on panic. > > + crashkernel=size[KMG][@offset[KMG]] > > + [KNL] Using kexec, Linux can switch to a 'crash kernel' > > + upon panic. This parameter reserves the physical > > + memory region [offset, offset + size] for that kernel > > + image. If the '@offset' part was ignored, Linux finds > > + a suitable crash image start address automatically. > > I think this would be further improved as: > > ... If '@offset' is omitted then a suitable > offset is selected automatically. > > > > > crashkernel=range1:size1[,range2:size2,...][@offset] > > [KNL] Same as above, but depends on the memory Hi, I also prefer Simon's change. Can you please resend an updated patch? thanks, --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply [flat|nested] 25+ messages in thread
* [PATCH v2 -next] Documentation: Improve crashkernel= description 2011-02-07 4:14 ` Randy Dunlap @ 2011-02-07 11:30 ` Ahmed S. Darwish -1 siblings, 0 replies; 25+ messages in thread From: Ahmed S. Darwish @ 2011-02-07 11:30 UTC (permalink / raw) To: Randy Dunlap Cc: Simon Horman, Vivek Goyal, Haren Myneni, Eric Biederman, kexec, LKML, linux-doc Had to explore two C code files to make sense of the 'crashkernel=' kernel parameter values. Improve the situation. Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> --- diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 89835a4..5ad9980 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] - crashkernel=nn[KMG]@ss[KMG] - [KNL] Reserve a chunk of physical memory to - hold a kernel to switch to with kexec on panic. + crashkernel=size[KMG][@offset[KMG]] + [KNL] Using kexec, Linux can switch to a 'crash kernel' + upon panic. This parameter reserves the physical + memory region [offset, offset + size] for that kernel + image. If '@offset' is omitted, then a suitable offset + is selected automatically. crashkernel=range1:size1[,range2:size2,...][@offset] [KNL] Same as above, but depends on the memory -- Darwish http://darwish.07.googlepages.com ^ permalink raw reply related [flat|nested] 25+ messages in thread
* [PATCH v2 -next] Documentation: Improve crashkernel= description @ 2011-02-07 11:30 ` Ahmed S. Darwish 0 siblings, 0 replies; 25+ messages in thread From: Ahmed S. Darwish @ 2011-02-07 11:30 UTC (permalink / raw) To: Randy Dunlap Cc: linux-doc, kexec, LKML, Haren Myneni, Simon Horman, Eric Biederman, Vivek Goyal Had to explore two C code files to make sense of the 'crashkernel=' kernel parameter values. Improve the situation. Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> --- diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 89835a4..5ad9980 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] - crashkernel=nn[KMG]@ss[KMG] - [KNL] Reserve a chunk of physical memory to - hold a kernel to switch to with kexec on panic. + crashkernel=size[KMG][@offset[KMG]] + [KNL] Using kexec, Linux can switch to a 'crash kernel' + upon panic. This parameter reserves the physical + memory region [offset, offset + size] for that kernel + image. If '@offset' is omitted, then a suitable offset + is selected automatically. crashkernel=range1:size1[,range2:size2,...][@offset] [KNL] Same as above, but depends on the memory -- Darwish http://darwish.07.googlepages.com _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply related [flat|nested] 25+ messages in thread
* Re: [PATCH v2 -next] Documentation: Improve crashkernel= description 2011-02-07 11:30 ` Ahmed S. Darwish @ 2011-02-07 11:41 ` Simon Horman -1 siblings, 0 replies; 25+ messages in thread From: Simon Horman @ 2011-02-07 11:41 UTC (permalink / raw) To: Ahmed S. Darwish Cc: Randy Dunlap, Vivek Goyal, Haren Myneni, Eric Biederman, kexec, LKML, linux-doc On Mon, Feb 07, 2011 at 01:30:54PM +0200, Ahmed S. Darwish wrote: > > Had to explore two C code files to make sense of the 'crashkernel=' > kernel parameter values. Improve the situation. > > Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> Thanks, that looks looks a good improvement over the existing documentation. Acked-by: Simon Horman <horms@verge.net.au> > --- > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 89835a4..5ad9980 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > Format: > <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > - crashkernel=nn[KMG]@ss[KMG] > - [KNL] Reserve a chunk of physical memory to > - hold a kernel to switch to with kexec on panic. > + crashkernel=size[KMG][@offset[KMG]] > + [KNL] Using kexec, Linux can switch to a 'crash kernel' > + upon panic. This parameter reserves the physical > + memory region [offset, offset + size] for that kernel > + image. If '@offset' is omitted, then a suitable offset > + is selected automatically. > > crashkernel=range1:size1[,range2:size2,...][@offset] > [KNL] Same as above, but depends on the memory > > -- > Darwish > http://darwish.07.googlepages.com > ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v2 -next] Documentation: Improve crashkernel= description @ 2011-02-07 11:41 ` Simon Horman 0 siblings, 0 replies; 25+ messages in thread From: Simon Horman @ 2011-02-07 11:41 UTC (permalink / raw) To: Ahmed S. Darwish Cc: linux-doc, kexec, LKML, Haren Myneni, Randy Dunlap, Eric Biederman, Vivek Goyal On Mon, Feb 07, 2011 at 01:30:54PM +0200, Ahmed S. Darwish wrote: > > Had to explore two C code files to make sense of the 'crashkernel=' > kernel parameter values. Improve the situation. > > Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> Thanks, that looks looks a good improvement over the existing documentation. Acked-by: Simon Horman <horms@verge.net.au> > --- > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 89835a4..5ad9980 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > Format: > <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > - crashkernel=nn[KMG]@ss[KMG] > - [KNL] Reserve a chunk of physical memory to > - hold a kernel to switch to with kexec on panic. > + crashkernel=size[KMG][@offset[KMG]] > + [KNL] Using kexec, Linux can switch to a 'crash kernel' > + upon panic. This parameter reserves the physical > + memory region [offset, offset + size] for that kernel > + image. If '@offset' is omitted, then a suitable offset > + is selected automatically. > > crashkernel=range1:size1[,range2:size2,...][@offset] > [KNL] Same as above, but depends on the memory > > -- > Darwish > http://darwish.07.googlepages.com > _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v2 -next] Documentation: Improve crashkernel= description 2011-02-07 11:30 ` Ahmed S. Darwish @ 2011-02-07 14:25 ` Vivek Goyal -1 siblings, 0 replies; 25+ messages in thread From: Vivek Goyal @ 2011-02-07 14:25 UTC (permalink / raw) To: Ahmed S. Darwish Cc: Randy Dunlap, Simon Horman, Haren Myneni, Eric Biederman, kexec, LKML, linux-doc On Mon, Feb 07, 2011 at 01:30:54PM +0200, Ahmed S. Darwish wrote: > > Had to explore two C code files to make sense of the 'crashkernel=' > kernel parameter values. Improve the situation. > Did you look at Documentation/kdump/kdump.txt before looking into the code. I thought kdump.txt explained the meaning of crashkernel= well. In case if it was not obivious that for further details look into kdump.txt, I will suggest to add a line asking reader to look into kdump.txt for more details. Tough crashkernel= range1:size1[,range2:size2,...][@offset], description in next line already mentions kdump.txt This patch looks good to me as it is though. Acked-by: Vivek Goyal <vgoyal@redhat.com> Vivek > Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > --- > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 89835a4..5ad9980 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > Format: > <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > - crashkernel=nn[KMG]@ss[KMG] > - [KNL] Reserve a chunk of physical memory to > - hold a kernel to switch to with kexec on panic. > + crashkernel=size[KMG][@offset[KMG]] > + [KNL] Using kexec, Linux can switch to a 'crash kernel' > + upon panic. This parameter reserves the physical > + memory region [offset, offset + size] for that kernel > + image. If '@offset' is omitted, then a suitable offset > + is selected automatically. > > crashkernel=range1:size1[,range2:size2,...][@offset] > [KNL] Same as above, but depends on the memory > > -- > Darwish > http://darwish.07.googlepages.com ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v2 -next] Documentation: Improve crashkernel= description @ 2011-02-07 14:25 ` Vivek Goyal 0 siblings, 0 replies; 25+ messages in thread From: Vivek Goyal @ 2011-02-07 14:25 UTC (permalink / raw) To: Ahmed S. Darwish Cc: linux-doc, kexec, LKML, Haren Myneni, Randy Dunlap, Simon Horman, Eric Biederman On Mon, Feb 07, 2011 at 01:30:54PM +0200, Ahmed S. Darwish wrote: > > Had to explore two C code files to make sense of the 'crashkernel=' > kernel parameter values. Improve the situation. > Did you look at Documentation/kdump/kdump.txt before looking into the code. I thought kdump.txt explained the meaning of crashkernel= well. In case if it was not obivious that for further details look into kdump.txt, I will suggest to add a line asking reader to look into kdump.txt for more details. Tough crashkernel= range1:size1[,range2:size2,...][@offset], description in next line already mentions kdump.txt This patch looks good to me as it is though. Acked-by: Vivek Goyal <vgoyal@redhat.com> Vivek > Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > --- > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 89835a4..5ad9980 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -545,9 +545,12 @@ and is between 256 and 4096 characters. It is defined in the file > Format: > <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > - crashkernel=nn[KMG]@ss[KMG] > - [KNL] Reserve a chunk of physical memory to > - hold a kernel to switch to with kexec on panic. > + crashkernel=size[KMG][@offset[KMG]] > + [KNL] Using kexec, Linux can switch to a 'crash kernel' > + upon panic. This parameter reserves the physical > + memory region [offset, offset + size] for that kernel > + image. If '@offset' is omitted, then a suitable offset > + is selected automatically. > > crashkernel=range1:size1[,range2:size2,...][@offset] > [KNL] Same as above, but depends on the memory > > -- > Darwish > http://darwish.07.googlepages.com _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply [flat|nested] 25+ messages in thread
* [PATCH v3 -next] Documentation: Improve crashkernel= description 2011-02-07 14:25 ` Vivek Goyal @ 2011-02-07 16:01 ` Ahmed S. Darwish -1 siblings, 0 replies; 25+ messages in thread From: Ahmed S. Darwish @ 2011-02-07 16:01 UTC (permalink / raw) To: Vivek Goyal Cc: Randy Dunlap, Simon Horman, Haren Myneni, Eric Biederman, kexec, LKML, linux-doc On Mon, Feb 07, 2011 at 09:25:50AM -0500, Vivek Goyal wrote: > On Mon, Feb 07, 2011 at 01:30:54PM +0200, Ahmed S. Darwish wrote: > > > > Had to explore two C code files to make sense of the 'crashkernel=' > > kernel parameter values. Improve the situation. > > > > Did you look at Documentation/kdump/kdump.txt before looking into the > code. I thought kdump.txt explained the meaning of crashkernel= well. > > In case if it was not obivious that for further details look into > kdump.txt, I will suggest to add a line asking reader to look into > kdump.txt for more details. > Yes, I jumped to the code first :-) Here's a new patch with the link: (Also applicable over latest -rc3) ==> Complete the crashkernel= kernel parameter documentation. Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> --- diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 89835a4..050b0e5 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -545,16 +545,20 @@ and is between 256 and 4096 characters. It is defined in the file Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] - crashkernel=nn[KMG]@ss[KMG] - [KNL] Reserve a chunk of physical memory to - hold a kernel to switch to with kexec on panic. + crashkernel=size[KMG][@offset[KMG]] + [KNL] Using kexec, Linux can switch to a 'crash kernel' + upon panic. This parameter reserves the physical + memory region [offset, offset + size] for that kernel + image. If '@offset' is omitted, then a suitable offset + is selected automatically. Check + Documentation/kdump/kdump.txt for further details. crashkernel=range1:size1[,range2:size2,...][@offset] [KNL] Same as above, but depends on the memory in the running system. The syntax of range is start-[end] where start and end are both a memory unit (amount[KMG]). See also - Documentation/kdump/kdump.txt for a example. + Documentation/kdump/kdump.txt for an example. cs89x0_dma= [HW,NET] Format: <dma> > > Acked-by: Vivek Goyal <vgoyal@redhat.com> > thanks, -- Darwish http://darwish.07.googlepages.com ^ permalink raw reply related [flat|nested] 25+ messages in thread
* [PATCH v3 -next] Documentation: Improve crashkernel= description @ 2011-02-07 16:01 ` Ahmed S. Darwish 0 siblings, 0 replies; 25+ messages in thread From: Ahmed S. Darwish @ 2011-02-07 16:01 UTC (permalink / raw) To: Vivek Goyal Cc: linux-doc, kexec, LKML, Haren Myneni, Randy Dunlap, Simon Horman, Eric Biederman On Mon, Feb 07, 2011 at 09:25:50AM -0500, Vivek Goyal wrote: > On Mon, Feb 07, 2011 at 01:30:54PM +0200, Ahmed S. Darwish wrote: > > > > Had to explore two C code files to make sense of the 'crashkernel=' > > kernel parameter values. Improve the situation. > > > > Did you look at Documentation/kdump/kdump.txt before looking into the > code. I thought kdump.txt explained the meaning of crashkernel= well. > > In case if it was not obivious that for further details look into > kdump.txt, I will suggest to add a line asking reader to look into > kdump.txt for more details. > Yes, I jumped to the code first :-) Here's a new patch with the link: (Also applicable over latest -rc3) ==> Complete the crashkernel= kernel parameter documentation. Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> --- diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt index 89835a4..050b0e5 100644 --- a/Documentation/kernel-parameters.txt +++ b/Documentation/kernel-parameters.txt @@ -545,16 +545,20 @@ and is between 256 and 4096 characters. It is defined in the file Format: <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] - crashkernel=nn[KMG]@ss[KMG] - [KNL] Reserve a chunk of physical memory to - hold a kernel to switch to with kexec on panic. + crashkernel=size[KMG][@offset[KMG]] + [KNL] Using kexec, Linux can switch to a 'crash kernel' + upon panic. This parameter reserves the physical + memory region [offset, offset + size] for that kernel + image. If '@offset' is omitted, then a suitable offset + is selected automatically. Check + Documentation/kdump/kdump.txt for further details. crashkernel=range1:size1[,range2:size2,...][@offset] [KNL] Same as above, but depends on the memory in the running system. The syntax of range is start-[end] where start and end are both a memory unit (amount[KMG]). See also - Documentation/kdump/kdump.txt for a example. + Documentation/kdump/kdump.txt for an example. cs89x0_dma= [HW,NET] Format: <dma> > > Acked-by: Vivek Goyal <vgoyal@redhat.com> > thanks, -- Darwish http://darwish.07.googlepages.com _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply related [flat|nested] 25+ messages in thread
* Re: [PATCH v3 -next] Documentation: Improve crashkernel= description 2011-02-07 16:01 ` Ahmed S. Darwish @ 2011-02-08 18:50 ` Randy Dunlap -1 siblings, 0 replies; 25+ messages in thread From: Randy Dunlap @ 2011-02-08 18:50 UTC (permalink / raw) To: Ahmed S. Darwish Cc: Vivek Goyal, Simon Horman, Haren Myneni, Eric Biederman, kexec, LKML, linux-doc On Mon, 7 Feb 2011 18:01:27 +0200 Ahmed S. Darwish wrote: > On Mon, Feb 07, 2011 at 09:25:50AM -0500, Vivek Goyal wrote: > > On Mon, Feb 07, 2011 at 01:30:54PM +0200, Ahmed S. Darwish wrote: > > > > > > Had to explore two C code files to make sense of the 'crashkernel=' > > > kernel parameter values. Improve the situation. > > > > > > > Did you look at Documentation/kdump/kdump.txt before looking into the > > code. I thought kdump.txt explained the meaning of crashkernel= well. > > > > In case if it was not obivious that for further details look into > > kdump.txt, I will suggest to add a line asking reader to look into > > kdump.txt for more details. > > > > Yes, I jumped to the code first :-) Here's a new patch with the link: > > (Also applicable over latest -rc3) > > ==> > > Complete the crashkernel= kernel parameter documentation. > > Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > --- > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 89835a4..050b0e5 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -545,16 +545,20 @@ and is between 256 and 4096 characters. It is defined in the file > Format: > <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > - crashkernel=nn[KMG]@ss[KMG] > - [KNL] Reserve a chunk of physical memory to > - hold a kernel to switch to with kexec on panic. > + crashkernel=size[KMG][@offset[KMG]] > + [KNL] Using kexec, Linux can switch to a 'crash kernel' > + upon panic. This parameter reserves the physical > + memory region [offset, offset + size] for that kernel > + image. If '@offset' is omitted, then a suitable offset > + is selected automatically. Check > + Documentation/kdump/kdump.txt for further details. > > crashkernel=range1:size1[,range2:size2,...][@offset] > [KNL] Same as above, but depends on the memory > in the running system. The syntax of range is > start-[end] where start and end are both > a memory unit (amount[KMG]). See also > - Documentation/kdump/kdump.txt for a example. > + Documentation/kdump/kdump.txt for an example. > > cs89x0_dma= [HW,NET] > Format: <dma> > > > > > > Acked-by: Vivek Goyal <vgoyal@redhat.com> Applied v3, along with your KMG info patch. Thanks. --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** ^ permalink raw reply [flat|nested] 25+ messages in thread
* Re: [PATCH v3 -next] Documentation: Improve crashkernel= description @ 2011-02-08 18:50 ` Randy Dunlap 0 siblings, 0 replies; 25+ messages in thread From: Randy Dunlap @ 2011-02-08 18:50 UTC (permalink / raw) To: Ahmed S. Darwish Cc: linux-doc, kexec, LKML, Haren Myneni, Simon Horman, Eric Biederman, Vivek Goyal On Mon, 7 Feb 2011 18:01:27 +0200 Ahmed S. Darwish wrote: > On Mon, Feb 07, 2011 at 09:25:50AM -0500, Vivek Goyal wrote: > > On Mon, Feb 07, 2011 at 01:30:54PM +0200, Ahmed S. Darwish wrote: > > > > > > Had to explore two C code files to make sense of the 'crashkernel=' > > > kernel parameter values. Improve the situation. > > > > > > > Did you look at Documentation/kdump/kdump.txt before looking into the > > code. I thought kdump.txt explained the meaning of crashkernel= well. > > > > In case if it was not obivious that for further details look into > > kdump.txt, I will suggest to add a line asking reader to look into > > kdump.txt for more details. > > > > Yes, I jumped to the code first :-) Here's a new patch with the link: > > (Also applicable over latest -rc3) > > ==> > > Complete the crashkernel= kernel parameter documentation. > > Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com> > --- > > diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt > index 89835a4..050b0e5 100644 > --- a/Documentation/kernel-parameters.txt > +++ b/Documentation/kernel-parameters.txt > @@ -545,16 +545,20 @@ and is between 256 and 4096 characters. It is defined in the file > Format: > <first_slot>,<last_slot>,<port>,<enum_bit>[,<debug>] > > - crashkernel=nn[KMG]@ss[KMG] > - [KNL] Reserve a chunk of physical memory to > - hold a kernel to switch to with kexec on panic. > + crashkernel=size[KMG][@offset[KMG]] > + [KNL] Using kexec, Linux can switch to a 'crash kernel' > + upon panic. This parameter reserves the physical > + memory region [offset, offset + size] for that kernel > + image. If '@offset' is omitted, then a suitable offset > + is selected automatically. Check > + Documentation/kdump/kdump.txt for further details. > > crashkernel=range1:size1[,range2:size2,...][@offset] > [KNL] Same as above, but depends on the memory > in the running system. The syntax of range is > start-[end] where start and end are both > a memory unit (amount[KMG]). See also > - Documentation/kdump/kdump.txt for a example. > + Documentation/kdump/kdump.txt for an example. > > cs89x0_dma= [HW,NET] > Format: <dma> > > > > > > Acked-by: Vivek Goyal <vgoyal@redhat.com> Applied v3, along with your KMG info patch. Thanks. --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code *** _______________________________________________ kexec mailing list kexec@lists.infradead.org http://lists.infradead.org/mailman/listinfo/kexec ^ permalink raw reply [flat|nested] 25+ messages in thread
end of thread, other threads:[~2011-02-08 18:51 UTC | newest] Thread overview: 25+ messages (download: mbox.gz / follow: Atom feed) -- links below jump to the message on this page -- 2011-02-06 15:41 [PATCH -next] Documentation: Improve crashkernel= description Ahmed S. Darwish 2011-02-06 15:41 ` Ahmed S. Darwish 2011-02-06 21:57 ` Simon Horman 2011-02-06 21:57 ` Simon Horman 2011-02-07 2:25 ` Rob Landley 2011-02-07 2:25 ` Rob Landley 2011-02-07 2:35 ` Eric W. Biederman 2011-02-07 2:35 ` Eric W. Biederman 2011-02-07 2:42 ` Simon Horman 2011-02-07 2:42 ` Simon Horman 2011-02-07 14:33 ` Vivek Goyal 2011-02-07 14:33 ` Vivek Goyal 2011-02-07 10:59 ` WANG Cong 2011-02-07 4:14 ` Randy Dunlap 2011-02-07 4:14 ` Randy Dunlap 2011-02-07 11:30 ` [PATCH v2 " Ahmed S. Darwish 2011-02-07 11:30 ` Ahmed S. Darwish 2011-02-07 11:41 ` Simon Horman 2011-02-07 11:41 ` Simon Horman 2011-02-07 14:25 ` Vivek Goyal 2011-02-07 14:25 ` Vivek Goyal 2011-02-07 16:01 ` [PATCH v3 " Ahmed S. Darwish 2011-02-07 16:01 ` Ahmed S. Darwish 2011-02-08 18:50 ` Randy Dunlap 2011-02-08 18:50 ` Randy Dunlap
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