Re: [PATCH] efi: bump up EFI_MMAP_NR_SLACK_SLOTS to 32

[Ard Biesheuvel]

On Mon, 9 Dec 2024 at 19:20, Hamza Mahfooz
<hamzamahfooz@xxxxxxxxxxxxxxxxxxx> wrote:
>
> Recent platforms require more slack slots than the current value of
> EFI_MMAP_NR_SLACK_SLOTS, otherwise they fail to boot. The current
> workaround is to append `efi=disable_early_pci_dma` to the kernel's
> cmdline. So, bump up EFI_MMAP_NR_SLACK_SLOTS to 32 to allow those
> platforms to boot with the aforementioned workaround.
>
> Cc: stable@xxxxxxxxxx
> Cc: Ard Biesheuvel <ardb@xxxxxxxxxx>
> Cc: Allen Pais <apais@xxxxxxxxxxxxxxxxxxx>
> Cc: Tyler Hicks <code@xxxxxxxxxxx>
> Signed-off-by: Hamza Mahfooz <hamzamahfooz@xxxxxxxxxxxxxxxxxxx>
> ---
>  drivers/firmware/efi/libstub/efistub.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/firmware/efi/libstub/efistub.h b/drivers/firmware/efi/libstub/efistub.h
> index 76e44c185f29..e95ce6ae5c26 100644
> --- a/drivers/firmware/efi/libstub/efistub.h
> +++ b/drivers/firmware/efi/libstub/efistub.h
> @@ -171,7 +171,7 @@ void efi_set_u64_split(u64 data, u32 *lo, u32 *hi)
>   * the EFI memory map. Other related structures, e.g. x86 e820ext, need
>   * to factor in this headroom requirement as well.
>   */
> -#define EFI_MMAP_NR_SLACK_SLOTS        8
> +#define EFI_MMAP_NR_SLACK_SLOTS        32
>
>  typedef struct efi_generic_dev_path efi_device_path_protocol_t;
>

Acked-by: Ard Biesheuvel <ardb@xxxxxxxxxx>