Persistent Variable Storage and PlatformBootTimeOut

Persistent Variable Storage and PlatformBootTimeOut

[Bhupesh Sharma]

Hi EDK2 experts,

We have recently added the support for storing UEFI run-time variables on underlying NOR
Flash slave on our ARMV8 NXP board.

We are successfully able to change the values of variables like boot-order using the latest
MdeModulePkg BDS:

	MdeModulePkg/Universal/BdsDxe/BdsDxe.inf

and retrieve them on next board boot.

While this works almost on all the places, we see that the Auto Boot Time we have set using the
following PCD:
	gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|20

Doesn't work when one enters the BIOS screen and enters the Boot Maintenance Manager to change this
value from say 20 to 10.

On the next board boot, the PlatformBootTimeOut value is still 20.

The same issue is replicable on latest EDK2 (master branch) on qemu for aarch64.

Is this a known issue or are we missing something here?

Regards,
Bhupesh

Re: Persistent Variable Storage and PlatformBootTimeOut

[Ard Biesheuvel]

On 6 September 2016 at 12:13, Bhupesh Sharma <bhupesh.sharma@nxp.com> wrote:
> Hi EDK2 experts,
>
> We have recently added the support for storing UEFI run-time variables on underlying NOR
> Flash slave on our ARMV8 NXP board.
>
> We are successfully able to change the values of variables like boot-order using the latest
> MdeModulePkg BDS:
>
>         MdeModulePkg/Universal/BdsDxe/BdsDxe.inf
>
> and retrieve them on next board boot.
>
> While this works almost on all the places, we see that the Auto Boot Time we have set using the
> following PCD:
>         gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|20
>
> Doesn't work when one enters the BIOS screen and enters the Boot Maintenance Manager to change this
> value from say 20 to 10.
>
> On the next board boot, the PlatformBootTimeOut value is still 20.
>
> The same issue is replicable on latest EDK2 (master branch) on qemu for aarch64.
>
> Is this a known issue or are we missing something here?
>

You should declare it as

[PcdsDynamicHii.common.DEFAULT]
  gEfiMdePkgTokenSpaceGuid.PcdPlatformBootTimeOut|L"Timeout"|gEfiGlobalVariableGuid|0x0|10
# Variable: L"Timeout"

to connect the dynamic PCD to the EFI variable.