-----Original Message-----
> On arm64, memory section size changes due to the kernel commit
> f0b13ee23241 ("arm64/sparsemem: reduce SECTION_SIZE_BITS")
>
> To tackle the compatibility, it is safe to read this info from sysfs
> "/sys/devices/system/memory/block_size_bytes"
Thanks for the patch, but the place where we should put/get such
necessary information first is vmcoreinfo, which exists for that.
Can we add an entry for the SECTIONS_SIZE_BITS there?
If we use information from a runtime environment, makedumpfile cannot
process vmcores/dumpfiles generated from other kernels than one that
makedumpfile is running.
Thanks,
Kazu
>
> Signed-off-by: Pingfan Liu <piliu@xxxxxxxxxx>
> Cc: Kazuhito Hagio <k-hagio-ab@xxxxxxx>
> To: kexec@xxxxxxxxxxxxxxxxxxx
> ---
> arch/arm64.c | 21 ++++++++++++++++++++-
> 1 file changed, 20 insertions(+), 1 deletion(-)
>
> diff --git a/arch/arm64.c b/arch/arm64.c
> index 1072178..2f6f5cf 100644
> --- a/arch/arm64.c
> +++ b/arch/arm64.c
> @@ -424,6 +424,11 @@ get_page_offset_arm64(void)
> int
> get_machdep_info_arm64(void)
> {
> + const char sys_path_section_sz[] = "/sys/devices/system/memory/block_size_bytes";
> + char memsection_sz_str[64] = { 0 };
> + unsigned long memsection_sz = 0;
> + FILE *fp;
> +
> /* Check if va_bits is still not initialized. If still 0, call
> * get_versiondep_info() to initialize the same.
> */
> @@ -451,7 +456,21 @@ get_machdep_info_arm64(void)
> }
>
> kimage_voffset = NUMBER(kimage_voffset);
> - info->section_size_bits = SECTIONS_SIZE_BITS;
> +
> + fp = fopen(sys_path_section_sz, "r");
> + if (fp) {
> + int i;
> +
> + fread(&memsection_sz_str, 64, 1, fp);
> + fclose(fp);
> + memsection_sz = strtol(memsection_sz_str, NULL, 16);
> + for (i = -1; memsection_sz != 0; i++)
> + memsection_sz >>= 1;
> + info->section_size_bits = i;
> + }
> + else {
> + info->section_size_bits = SECTIONS_SIZE_BITS;
> + }
>
> DEBUG_MSG("kimage_voffset : %lx\n", kimage_voffset);
> DEBUG_MSG("section_size_bits: %ld\n", info->section_size_bits);
> --
> 2.29.2
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