Re: [PATCH V5 0/4] Handle EFI_INVALID_PARAMETER from ExitBootServices

[Matt Fleming <matt-mF/unelCI9GS6iBeEJttW/XRex20P6io@public.gmane.org>]

On Mon, 29 Aug, at 02:38:50PM, Jeffrey Hugo wrote:
> According to the UEFI spec, the UEFI OS Loader (aka the stub) should
> transition from UEFI to the OS by getting the current memory map from UEFI,
> then calling ExitBootServices.  The spec states that ExitBootServices may
> return EFI_INVALID_PARAMETER if the memory map reference provided by the stub
> is not current, ie UEFI handled some event prior to ExitBootServices which
> modified the map.  The spec states that to handle this scenario, the stub shall
> get the updated map, and invoke ExitBootServices again.  The spec also states
> that once ExitBootServices is invoked, even if it returns error, the only
> APIs the stub is allowed to invoke is GetMemoryMap and ExitBootServices.
> 
> The EFI_INVALID_PARAMETER scenario has been seen in the wild previously in
> x86 but the fix - d3768d885c6c ("x86, efi: retry ExitBootServices() on failure")
> still violates the spec.  The FDT code does not handle this scenario, but
> instances of it are now observed.
> 
> This patch series aims to provide a spec complaint solution that can be reused
> in all stubs, thus preventing each arch or variant from reinventing the wheel
> and likely getting it wrong.

Thanks Jeffrey, applied.