Hello Simon,
what's up with this patch? Do you plan to apply it, or is there still
an issue?
Regards,
Petr Tesarik
On Thu, 24 Sep 2015 08:48:52 +0200
Petr Tesarik <ptesarik at suse.com> wrote:
> There may be more than one crash kernel regions on x86. Currently,
> kexec-tools picks the largest one. If high reservation is smaller
> than low, it will try to load panic kernel low. However, the kexec
> syscall checks that target address is within crashk_res boundaries,
> so attempts to load crash kernel low result in -EADDRNOTAVAIL, and
> kexec prints out this error message:
>
> kexec_load failed: Cannot assign requested address
>
> Looking at the logic in arch/x86/kernel/setup.c, there are only two
> possible layouts:
>
> 1. crashk_res is below 4G, and there is only one region,
> 2. crashk_res is above 4G, and crashk_low_res is below 4G
>
> In either case, kexec-tools must pick the highest region.
>
> Changelog:
>
> * v3: rename function to get_crash_kernel_load_range
> * v2: remove unnecessary local variables
>
> Signed-off-by: Petr Tesarik <ptesarik at suse.com>
>
> ---
> kexec/arch/i386/crashdump-x86.c | 21 +++++++--------------
> kexec/arch/i386/kexec-x86-common.c | 4 ++--
> kexec/kexec.h | 2 +-
> 3 files changed, 10 insertions(+), 17 deletions(-)
>
> diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
> index 63959b7..d4969c5 100644
> --- a/kexec/arch/i386/crashdump-x86.c
> +++ b/kexec/arch/i386/crashdump-x86.c
> @@ -1026,24 +1026,17 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
> return 0;
> }
>
> -int get_max_crash_kernel_limit(uint64_t *start, uint64_t *end)
> +/* On x86, the kernel may make a low reservation in addition to the
> + * normal reservation. However, the kernel refuses to load the panic
> + * kernel to low memory, so always choose the highest range.
> + */
> +int get_crash_kernel_load_range(uint64_t *start, uint64_t *end)
> {
> - int i, idx = -1;
> - unsigned long sz_max = 0, sz;
> -
> if (!crash_reserved_mem_nr)
> return -1;
>
> - for (i = crash_reserved_mem_nr - 1; i >= 0; i--) {
> - sz = crash_reserved_mem[i].end - crash_reserved_mem[i].start +1;
> - if (sz <= sz_max)
> - continue;
> - sz_max = sz;
> - idx = i;
> - }
> -
> - *start = crash_reserved_mem[idx].start;
> - *end = crash_reserved_mem[idx].end;
> + *start = crash_reserved_mem[crash_reserved_mem_nr - 1].start;
> + *end = crash_reserved_mem[crash_reserved_mem_nr - 1].end;
>
> return 0;
> }
> diff --git a/kexec/arch/i386/kexec-x86-common.c b/kexec/arch/i386/kexec-x86-common.c
> index 041c8ec..484d712 100644
> --- a/kexec/arch/i386/kexec-x86-common.c
> +++ b/kexec/arch/i386/kexec-x86-common.c
> @@ -371,9 +371,9 @@ int get_memory_ranges(struct memory_range **range, int *ranges,
> !(kexec_flags & KEXEC_PRESERVE_CONTEXT)) {
> uint64_t start, end;
>
> - ret = get_max_crash_kernel_limit(&start, &end);
> + ret = get_crash_kernel_load_range(&start, &end);
> if (ret != 0) {
> - fprintf(stderr, "get_max_crash_kernel_limit failed.\n");
> + fprintf(stderr, "get_crash_kernel_load_range failed.\n");
> return -1;
> }
>
> diff --git a/kexec/kexec.h b/kexec/kexec.h
> index 0fa977f..7c97b25 100644
> --- a/kexec/kexec.h
> +++ b/kexec/kexec.h
> @@ -288,7 +288,7 @@ int arch_process_options(int argc, char **argv);
> int arch_compat_trampoline(struct kexec_info *info);
> void arch_update_purgatory(struct kexec_info *info);
> int is_crashkernel_mem_reserved(void);
> -int get_max_crash_kernel_limit(uint64_t *start, uint64_t *end);
> +int get_crash_kernel_load_range(uint64_t *start, uint64_t *end);
> char *get_command_line(void);
>
> int kexec_iomem_for_each_line(char *match,
