Re: [PATCHv7] x86/kdump: bugfix, make the behavior of crashkernel=X consistent with kaslr

[Pingfan Liu]

Hi Borislav,

Do you think the following patch is good at present?
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 81f9d23..9213073 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -460,7 +460,7 @@ static void __init
memblock_x86_reserve_range_setup_data(void)
 # define CRASH_ADDR_LOW_MAX    (512 << 20)
 # define CRASH_ADDR_HIGH_MAX   (512 << 20)
 #else
-# define CRASH_ADDR_LOW_MAX    (896UL << 20)
+# define CRASH_ADDR_LOW_MAX    (1 << 32)
 # define CRASH_ADDR_HIGH_MAX   MAXMEM
 #endif

For documentation, I will send another patch to improve the description.

Thanks,
Pingfan

On Mon, Feb 25, 2019 at 7:30 PM Borislav Petkov <bp@xxxxxxxxx> wrote:
>
> On Mon, Feb 25, 2019 at 07:12:16PM +0800, Dave Young wrote:
> > If we move to high as default, it will allocate 160M high + 256M low. It
>
> We won't move to high by default - we will *fall* back to high if the
> default allocation fails.
>
> > To make the process less fragile maybe we can remove the 896M limitation
> > and only try <4G then go to high.
>
> Sure, the more robust for the user, the better.
>
> --
> Regards/Gruss,
>     Boris.
>
> Good mailing practices for 400: avoid top-posting and trim the reply.