lkml.org 
[lkml]   [2007]   [Mar]   [28]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [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/

    \
     
     \ /
      Last update: 2007-03-29 05:51    [W:0.023 / U:94.476 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site