Messages in this thread | | | Date | Thu, 29 Mar 2007 12:48:40 +0900 | From | Simon Horman <> | Subject | Re: [PATCH] kdump/kexec: calculate note size at compile time |
| |
On Thu, Mar 29, 2007 at 09:14:21AM +0530, Vivek Goyal wrote: > On Thu, Mar 29, 2007 at 12:30:59PM +0900, Simon Horman wrote: > > Hi, > > > > this is a(nother) minor update to this patch. > > Explanation below. > > > > -- > > Horms > > H: http://www.vergenet.net/~horms/ > > W: http://www.valinux.co.jp/en/ > > > > [PATCH] kdump/kexec: calculate note size at compile time > > > > Currently the size of the per-cpu region reserved to save crash > > notes is set by the per-architecture value MAX_NOTE_BYTES. Which > > in turn is currently set to 1024 on all supported architectures. > > > > While testing ia64 I recently discovered that this value is > > in fact too small. The particular setup I was using actually > > needs 1172 bytes. This lead to very tedious failure mode > > where the tail of one elf note would overwrite the head of > > another if they ended up being alocated sequentially by kmalloc, > > which was often the case. > > > > It seems to me that a far better approach is to caclculate the size > > that the area needs to be. This patch does just that. > > > > If a simpler stop-gap patch for ia64 to be squeezed into 2.6.21(.X) > > is needed then this should be as easy as making MAX_NOTE_BYTES > > larger in arch/asm-ia64/kexec.h. Perhaps 2048 would be a good choice. > > However, I think that the approach in this patch is a much more robust > > idea. > > > > Update I: > > > > Changed KEXEC_NOTE_HEAD_BYTES to KEXEC_NOTE_DESC_BYTES in line > > with the name of the relevant field in struct elf_note > > > > Update II: > > > > * Use KEXEC_NOTE_NAME instead of "CORE" in kernel/kexec.c and > > arch/ia64/kernel/crash.c just to be extra sure that the data > > used to calculate the size, and the data stuffed into the reserved > > area is the same. > > > > Incidently, the ia64 code really ought to use the generic code. > > I am working on a patch for this. But it is not urgent. > > > > Looks good. Another patch to make ia64 also use generic kexec code > for note generation would be nice.
Thanks, I will make it so :-)
-- Horms H: http://www.vergenet.net/~horms/ W: http://www.valinux.co.jp/en/
- 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/
| |