[SRU B/C/D/E][bionic/master-next 1/1] LP#1836079 efi: efi_get_memory_map -- increase map headroom

[Stefan Bader]

On 06.11.19 18:06, Andy Whitcroft wrote:
> We are seeing some EFI based machines failing to boot hard in the EFI
> stub:
> 
>     exit_boot() failed!
>     efi_main() failed!
> 
> This seems to occur when the bootloader (grub2 in this case) has had to
> manipulate some additional files.  We tracked this down to the memory map
> dance efi_get_memory_map().  Basically we attempt to close boot services
> and it informs us it cannot do so because it failed to record the updated
> memory map.  This occurs when there is insufficient space in the passed
> memory map buffer to record changes during the operation.  At the point
> when this occurs we are unable to reallocate the buffer so we panic.
> 
> To avoid this we allocate some additional entries in the buffer to cover
> any additional entries.  These are currently insufficient for these
> machines in this use case.  Increase EFI_MMAP_NR_SLACK_SLOTS to provide
> space for more map modifications.
> 
> BugLink: http://bugs.launchpad.net/bugs/1836079

^this is a private bug and we normally use https

> Signed-off-by: Andy Whitcroft <apw at canonical.com>
> ---
> 

also the subject is confusing having multible series (and btw, Cosmic is EOL)
and then again bionic...

 drivers/firmware/efi/libstub/efi-stub-helper.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/firmware/efi/libstub/efi-stub-helper.c b/drivers/firmware/efi/libstub/efi-stub-helper.c
> index 39f87e6dac5c..957dff5a26a2 100644
> --- a/drivers/firmware/efi/libstub/efi-stub-helper.c
> +++ b/drivers/firmware/efi/libstub/efi-stub-helper.c
> @@ -49,7 +49,7 @@ int __pure novamap(void)
>  	return __novamap;
>  }
>  
> -#define EFI_MMAP_NR_SLACK_SLOTS	8
> +#define EFI_MMAP_NR_SLACK_SLOTS	16
>  
>  struct file_info {
>  	efi_file_handle_t *handle;
> 


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