Hari Bathini <hbathini@xxxxxxxxxxxxx> writes:
> Though kdump kernel boots from loaded address, the first 64K bytes
> of it is copied down to real 0. So, setup a backup region to copy
> the first 64K bytes of crashed kernel, in purgatory, before booting
> into kdump kernel. Also, update reserve map with backup region and
> crashed kernel's memory to avoid kdump kernel from accidentially
> using that memory.
>
> Reported-by: kernel test robot <lkp@xxxxxxxxx>
> [lkp: In v1, purgatory() declaration was missing]
> Signed-off-by: Hari Bathini <hbathini@xxxxxxxxxxxxx>
Reviewed-by: Thiago Jung Bauermann <bauerman@xxxxxxxxxxxxx>
Just one minor comment below:
> @@ -1047,13 +1120,26 @@ int setup_new_fdt_ppc64(const struct kimage *image, void *fdt,
> goto out;
> }
>
> - /* Ensure we don't touch crashed kernel's memory */
> - ret = fdt_add_mem_rsv(fdt, 0, crashk_res.start);
> + /*
> + * Ensure we don't touch crashed kernel's memory except the
> + * first 64K of RAM, which will be backed up.
> + */
> + ret = fdt_add_mem_rsv(fdt, BACKUP_SRC_SIZE,
I know BACKUP_SRC_START is 0, but please forgive my pedantry when I say
that I think it's clearer if the start address above is changed to
BACKUP_SRC_START + BACKUP_SRC_SIZE...
> + crashk_res.start - BACKUP_SRC_SIZE);
> if (ret) {
> pr_err("Error reserving crash memory: %s\n",
> fdt_strerror(ret));
> goto out;
> }
> +
> + /* Ensure backup region is not used by kdump/capture kernel */
> + ret = fdt_add_mem_rsv(fdt, image->arch.backup_start,
> + BACKUP_SRC_SIZE);
> + if (ret) {
> + pr_err("Error reserving memory for backup: %s\n",
> + fdt_strerror(ret));
> + goto out;
> + }
> }
>
> out:
--
Thiago Jung Bauermann
IBM Linux Technology Center
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