Re: [PATCH v12 1/9] x86: kdump: move CRASH_ALIGN to 2M

Dave Young
2020-09-08T01:22:12Z

Hi,

On 09/07/20 at 09:47pm, Chen Zhou wrote:
> CONFIG_PHYSICAL_ALIGN can be selected from 2M to 16M and default
> value is 2M, so move CRASH_ALIGN to 2M, with smaller value reservation
> can have more chance to succeed.

Seems still some misunderstanding about the change :( I'm sorry if I
did not explain it clearly.

Previously I missed the PHYSICAL_ALIGN can change according to .config
I mean we should change the value to CONFIG_PHYSICAL_ALIGN for X86
And I suggest to move back to keep using 16M. And do not change it in
this series.

> And replace the hard-coded alignment with macro CRASH_ALIGN in function
> reserve_crashkernel().
>
> Suggested-by: Dave Young <dyoung@redhat.com>
> Signed-off-by: Chen Zhou <chenzhou10@huawei.com>
> ---
> arch/x86/include/asm/kexec.h | 3 +++
> arch/x86/kernel/setup.c | 5 +----
> 2 files changed, 4 insertions(+), 4 deletions(-)
>
> diff --git a/arch/x86/include/asm/kexec.h b/arch/x86/include/asm/kexec.h
> index 6802c59e8252..83f200dd54a1 100644
> --- a/arch/x86/include/asm/kexec.h
> +++ b/arch/x86/include/asm/kexec.h
> @@ -18,6 +18,9 @@
>
> # define KEXEC_CONTROL_CODE_MAX_SIZE 2048
>
> +/* 2M alignment for crash kernel regions */
> +#define CRASH_ALIGN SZ_2M
> +
> #ifndef __ASSEMBLY__
>
> #include <linux/string.h>
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 3511736fbc74..296294ad0dd8 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -402,9 +402,6 @@ static void __init memblock_x86_reserve_range_setup_data(void)
>
> #ifdef CONFIG_KEXEC_CORE
>
> -/* 16M alignment for crash kernel regions */
> -#define CRASH_ALIGN SZ_16M
> -
> /*
> * Keep the crash kernel below this limit.
> *
> @@ -530,7 +527,7 @@ static void __init reserve_crashkernel(void)
>
> start = memblock_find_in_range(crash_base,
> crash_base + crash_size,
> - crash_size, 1 << 20);
> + crash_size, CRASH_ALIGN);
> if (start != crash_base) {
> pr_info("crashkernel reservation failed - memory is in use.\n");
> return;
> --
> 2.20.1
>

Thanks
Dave