Re: [PATCH 05/10] StandaloneMmPkg/StandaloneMmCoreEntryPoint: drop explicit SerialPortLib call

[Achin Gupta <Achin.Gupta@arm.com>]

On Wed, Mar 06, 2019 at 05:41:30PM +0100, Ard Biesheuvel wrote:
> On Wed, 6 Mar 2019 at 17:35, Achin Gupta <Achin.Gupta@arm.com> wrote:
> >
> > Hi Ard,
> >
> > On Tue, Mar 05, 2019 at 02:32:43PM +0100, Ard Biesheuvel wrote:
> > > Sending DEBUG output to the serial port should only be done via
> > > DebugLib calls, which is in charge of initializing the serial
> > > port when appropriate. So drop the explicit SerialPortInitialize ()
> > > invocation, and rely on normal constructor ordering to get the
> > > serial port into the appropriate state at the right time.
> > >
> > > Contributed-under: TianoCore Contribution Agreement 1.1
> > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> > > ---
> > >  StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/AArch64/StandaloneMmCoreEntryPoint.c | 3 ---
> > >  1 file changed, 3 deletions(-)
> > >
> > > diff --git a/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/AArch64/StandaloneMmCoreEntryPoint.c b/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/AArch64/StandaloneMmCoreEntryPoint.c
> > > index 5cca532456fd..c8e11a253d24 100644
> > > --- a/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/AArch64/StandaloneMmCoreEntryPoint.c
> > > +++ b/StandaloneMmPkg/Library/StandaloneMmCoreEntryPoint/AArch64/StandaloneMmCoreEntryPoint.c
> > > @@ -232,9 +232,6 @@ _ModuleEntryPoint (
> > >    VOID                                    *TeData;
> > >    UINTN                                   TeDataSize;
> > >
> > > -  Status = SerialPortInitialize ();
> > > -  ASSERT_EFI_ERROR (Status);
> >
> > This is done in the first few instructions after EL3 ERETs into S-EL0 to
> > initialise the StMM partition. The constructors will be called a bit later. I
> > agree with the change but does EDK2 provide a mechanism for early prints to the
> > console in case we need this in future.
> >
>
> If so, the correct way to achieve this would be to call the DebugLib
> constructor by hand, and that should call the SerialPortLib
> constructor. Unfortunately, EDK2 is not put together like that, and
> especially constructor ordering is slightly broken.

Thanks!

Reviewed-by: achin.gupta@arm.com