Re: [PATCH v2] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel

Chao Fan
2019-04-03T07:30:33Z

On Wed, Apr 03, 2019 at 02:39:11PM +0800, Dave Young wrote:
>> Actually I got some different kexec test results.
>>
>> Yesterday, with my installed kernel (based on git head several weeks
>> ago), kexec kernel panics.
>>
>> Then I tried latest mainline with git pull, everything works, (with or
>> without the patch, and can not reproduce the bug this patch is fixing)
>>
>> Today, test again, kexec reboot hangs (with or without your patch), but
>> kdump works always (with or without the patch)
>>
>> It is weird to me. Probably I need find out why I can not reproduce the
>> bug this patch is addressing first.
>>
>> earlyprintk seems not working for me anymore, it is not easy to debug on
>> laptop now.
>>
>> But the patch itself is clear, I think it should be good. There might be
>> other things broken.
>
>Disable your immovable mem code then everything works for me. There
>might be something wrong in the code. Also "nokaslr" does not help, it
>should be another problem

If "nokaslr" doesn't help, so I think
>+ /*num_immovable_mem = count_immovable_mem_regions();*/
also doesn't help. I think the problem is from get_rsdp_addr().

You test it in your laptop, I only tested in Qemu guest.
I have no laptop avaliable, so I will look for a physical machine
to test it.

Thanks,
Chao Fan

>
>diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
>index 2e53c056ba20..e760c9159662 100644
>--- a/arch/x86/boot/compressed/kaslr.c
>+++ b/arch/x86/boot/compressed/kaslr.c
>@@ -416,7 +416,7 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
> handle_mem_options();
>
> /* Enumerate the immovable memory regions */
>- num_immovable_mem = count_immovable_mem_regions();
>+ /*num_immovable_mem = count_immovable_mem_regions();*/
>
> #ifdef CONFIG_X86_VERBOSE_BOOTUP
> /* Make sure video RAM can be used. */
>diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
>index c0d6c560df69..1bc6f46d3aa7 100644
>--- a/arch/x86/boot/compressed/misc.c
>+++ b/arch/x86/boot/compressed/misc.c
>@@ -352,7 +352,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
> boot_params->hdr.loadflags &= ~KASLR_FLAG;
>
> /* Save RSDP address for later use. */
>- boot_params->acpi_rsdp_addr = get_rsdp_addr();
>+/* boot_params->acpi_rsdp_addr = get_rsdp_addr(); */
>
> sanitize_boot_params(boot_params);
>
>
>