* [RFC] should BIOS change the efi type when we set CONFIG_X86_RESERVE_LOW ?
@ 2018-04-12 1:49 Xishi Qiu
2018-04-23 10:17 ` Xishi Qiu
0 siblings, 1 reply; 2+ messages in thread
From: Xishi Qiu @ 2018-04-12 1:49 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Ard Biesheuvel, H. Peter Anvin
Cc: yeyunfeng, Wenan Mao, Linux MM, LKML
Hi, I find CONFIG_X86_RESERVE_LOW=64 in my system, so trim_low_memory_range()
will reserve low 64kb memory. But efi_free_boot_services() will free it to
buddy system again later because BIOS set the type to EFI_BOOT_SERVICES_CODE.
Here is the log:
...
efi: mem03: type=3, attr=0xf, range=[0x000000000000e000-0x0000000000010000) (0MB
...
^ permalink raw reply [flat|nested] 2+ messages in thread
* Re: [RFC] should BIOS change the efi type when we set CONFIG_X86_RESERVE_LOW ?
2018-04-12 1:49 [RFC] should BIOS change the efi type when we set CONFIG_X86_RESERVE_LOW ? Xishi Qiu
@ 2018-04-23 10:17 ` Xishi Qiu
0 siblings, 0 replies; 2+ messages in thread
From: Xishi Qiu @ 2018-04-23 10:17 UTC (permalink / raw)
To: Thomas Gleixner, Ingo Molnar, Ard Biesheuvel, H. Peter Anvin
Cc: yeyunfeng, Wenan Mao, Linux MM, LKML
On 2018/4/12 9:49, Xishi Qiu wrote:
> Hi, I find CONFIG_X86_RESERVE_LOW=64 in my system, so trim_low_memory_range()
> will reserve low 64kb memory. But efi_free_boot_services() will free it to
> buddy system again later because BIOS set the type to EFI_BOOT_SERVICES_CODE.
>
> Here is the log:
> ...
> efi: mem03: type=3, attr=0xf, range=[0x000000000000e000-0x0000000000010000) (0MB
> ...
>
>
When call memblock_is_region_reserved(), it will set md->num_pages = 0 if the
memblock region is reserved. But trim_low_memory_range() reserve the region
after efi, so this breaks the logic, and efi_free_boot_services() will free
the pages(efi code/data). That means trim_low_memory_range() has not reserve
the low memory range.
...
efi_reserve_boot_services()
...
trim_low_memory_range()
...
efi_free_boot_services()
...
Shall we move trim_low_memory_range() before efi_reserve_boot_services()?
Thanks,
Xishi Qiu
> .
>
^ permalink raw reply [flat|nested] 2+ messages in thread
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2018-04-12 1:49 [RFC] should BIOS change the efi type when we set CONFIG_X86_RESERVE_LOW ? Xishi Qiu
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