[PATCH 0/3] vmcoreinfo support for dump filtering
akpm at linux-foundation.org
Wed Aug 22 18:40:36 EDT 2007
On Wed, 22 Aug 2007 21:08:38 +0900
"Ken'ichi Ohmichi" <oomichi at mxs.nes.nec.co.jp> wrote:
> Hi Andrew,
> This patch set frees the restriction that makedumpfile users should
> install a vmlinux file (including the debugging information) into
> each system.
> makedumpfile command is the dump filtering feature for kdump.
> It creates a small dumpfile by filtering unnecessary pages for the
> analysis. To distinguish unnecessary pages, it needs a vmlinux file
> including the debugging information. These days, the debugging package
> becomes a huge file, and it is hard to install it into each system.
> To solve the problem, kdump developers discussed it at lkml and kexec-ml.
> As the result, we reached the conclusion that necessary information
> for dump filtering (called "vmcoreinfo") should be embedded into the
> first kernel file and it should be accessed through /proc/vmcore
> during the second kernel.
> Dan Aloni created the patch set for the above implementation.
> And I updated it for multi architectures and memory models.
so... will this permit us to generate kdump files whcih don't have any
pagecache or anonymous memory in them?
> +void vmcoreinfo_append_str(const char *fmt, ...);
This should have suitable __attribute__s so that the compiler can check its
use. See many examples in include/linux/kernel.h, around line 120.
> +/* vmcoreinfo stuff */
> +unsigned char vmcoreinfo_data[VMCOREINFO_BYTES];
> +u32 vmcoreinfo_note[VMCOREINFO_NOTE_SIZE/4];
> +unsigned int vmcoreinfo_size = 0;
Please always run scripts/checkpatch.pl against your diffs.
> +unsigned int vmcoreinfo_max_size = sizeof(vmcoreinfo_data);
unsigned int = size_t? Perhaps vmcoreinfo_max_size should have size_t
> +void crash_save_vmcoreinfo(void)
> + u32 *buf;
> + if (!vmcoreinfo_size)
> + return;
> + vmcoreinfo_append_str("CRASHTIME=%d", xtime.tv_sec);
open-coded access to xtime probably isn't appropriate here. Consider using
get_seconds(). That might be more accurate on tickless kernels, too.
> + buf = (u32 *)vmcoreinfo_note;
> + buf = append_elf_note(buf, VMCOREINFO_NOTE_NAME, 0, vmcoreinfo_data,
> + vmcoreinfo_size);
> + final_note(buf);
> +static int __init crash_save_vmcoreinfo_init(void)
> + vmcoreinfo_append_str("OSRELEASE=%s\n", UTS_RELEASE);
> + vmcoreinfo_append_str("PAGESIZE=%d\n", PAGE_SIZE);
I expect the virtualisation guys would be bothered by an open-coded access
to UTS_RELEASE. I guess it doesn't matter much here, but perhaps it'd be
setting a better example to use init_uts_ns.name.release?
More information about the kexec