Re: [PATCH 2/3] ArmVirtPkg/FdtClientDxe: install DT configuration table at ReadyToBoot

[Laszlo Ersek <lersek@redhat.com>]

On 03/09/17 17:04, Ard Biesheuvel wrote:
> Wait for ReadyToBoot to install the FDT configuration table. This allows
> any driver to make modifications in the mean time, and will also allow us
> to defer the decision of whether to install it in the first place to later
> on in the boot.
> 
> Contributed-under: TianoCore Contribution Agreement 1.0
> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> ---
>  ArmVirtPkg/FdtClientDxe/FdtClientDxe.c   | 41 ++++++++++++++++----
>  ArmVirtPkg/FdtClientDxe/FdtClientDxe.inf |  1 +
>  2 files changed, 34 insertions(+), 8 deletions(-)
> 
> diff --git a/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c b/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c
> index 7cc0c44ca12a..0327af5739f2 100644
> --- a/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c
> +++ b/ArmVirtPkg/FdtClientDxe/FdtClientDxe.c
> @@ -303,6 +303,30 @@ STATIC FDT_CLIENT_PROTOCOL mFdtClientProtocol = {
>    GetOrInsertChosenNode,
>  };
>  
> +STATIC
> +VOID
> +EFIAPI
> +OnReadyToBoot (
> +  EFI_EVENT       Event,
> +  VOID            *Context
> +  )
> +{
> +  EFI_STATUS      Status;
> +
> +  if (!FeaturePcdGet (PcdPureAcpiBoot)) {
> +    //
> +    // Only install the FDT as a configuration table if we want to leave it up
> +    // to the OS to decide whether it prefers ACPI over DT.
> +    //
> +    Status = gBS->InstallConfigurationTable (&gFdtTableGuid, mDeviceTreeBase);
> +    ASSERT_EFI_ERROR (Status);
> +  }
> +
> +  gBS->CloseEvent (Event);

OK, you didn't forget to close the event. :)

> +}
> +
> +STATIC EFI_EVENT         ReadyToBootEvent;

This should be called "mReadyToBootEvent".

> +
>  EFI_STATUS
>  EFIAPI
>  InitializeFdtClientDxe (
> @@ -330,14 +354,15 @@ InitializeFdtClientDxe (
>  
>    DEBUG ((EFI_D_INFO, "%a: DTB @ 0x%p\n", __FUNCTION__, mDeviceTreeBase));
>  
> -  if (!FeaturePcdGet (PcdPureAcpiBoot)) {
> -    //
> -    // Only install the FDT as a configuration table if we want to leave it up
> -    // to the OS to decide whether it prefers ACPI over DT.
> -    //
> -    Status = gBS->InstallConfigurationTable (&gFdtTableGuid, DeviceTreeBase);
> -    ASSERT_EFI_ERROR (Status);
> -  }
> +  Status = gBS->CreateEventEx (
> +                  EVT_NOTIFY_SIGNAL,
> +                  TPL_CALLBACK,
> +                  OnReadyToBoot,
> +                  NULL,
> +                  &gEfiEventReadyToBootGuid,
> +                  &ReadyToBootEvent
> +                  );
> +  ASSERT_EFI_ERROR (Status);

I guess it's OK to insist that this succeed.

Also, this is done after the assignment to mDeviceTreeBase, so that's good.

>  
>    return gBS->InstallProtocolInterface (&ImageHandle, &gFdtClientProtocolGuid,
>                  EFI_NATIVE_INTERFACE, &mFdtClientProtocol);

However, if the protocol installation fails for any reason, we exit the
driver with an error code, and the driver will be unloaded. We'll have a
dangling callback pointer

In case of failure, the event should be closed (== CreateEventEx()
should be undone).

> diff --git a/ArmVirtPkg/FdtClientDxe/FdtClientDxe.inf b/ArmVirtPkg/FdtClientDxe/FdtClientDxe.inf
> index 3a0cd37040eb..00017727c32c 100644
> --- a/ArmVirtPkg/FdtClientDxe/FdtClientDxe.inf
> +++ b/ArmVirtPkg/FdtClientDxe/FdtClientDxe.inf
> @@ -42,6 +42,7 @@ [Protocols]
>    gFdtClientProtocolGuid                  ## PRODUCES
>  
>  [Guids]
> +  gEfiEventReadyToBootGuid
>    gFdtHobGuid
>    gFdtTableGuid
>  
> 

For completeness, can you please also

#include <Guid/EventGroup.h>

for gEfiEventReadyToBootGuid's sake, in the C file? (It is already
pulled in by something else, but, again, for completenes...)

Looks okay to me otherwise.

Thanks
Laszlo