ArmVirtualizationPkg: PlatformIntelBdsLib: fix multiconsole setup

ArmVirtualizationPkg: PlatformIntelBdsLib: fix multiconsole setup

In the following call chain:

PlatformBdsPolicyBehavior()
  PlatformBdsConnectConsole()
    InitializeConsolePipe() x 3
      BdsConnectDevicePath() [ArmPkg/Library/BdsLib/BdsFilePath.c]

the three InitializeConsolePipe() function calls pass through
- (&gST->ConsoleOutHandle, &gST->ConOut),
- (&gST->ConsoleInHandle, &gST->ConIn),
- (&gST->StandardErrorHandle, &gST->StdErr)

to BdsConnectDevicePath(), in ArmPkg's BdsLib.

At least when more than one console device paths are specified in the
ConIn / ConOut / ErrOut variables, the above resuls in:
- unchanged protocol interfaces (ConOut, ConIn, StdErr) in the system
  table (because ConSplitterDxe installs its non-NULL interfaces first),
- but, changed handles in the system table.

This effectively separates the handle fields in the system table from the
protocol interfaces in the same that should always be associated with the
handles. The end result is that clients using the handles break (splitting
/ multiplexing doesn't work for them), while clients directly using the
protocol interfaces work.

Therefore, do not attempt to connect consoles separately. ConSplitterDxe
is dispatched before PlatformBdsPolicyBehavior() is called (the latter
happens in the BDS phase), and ConSplitterDxe installs virtual handles and
protocol interfaces for input / output / error.

BdsLibConnectAll() covers all devices, including consoles; as those
consoles are connected, ConPlatformDxe and ConSplitterDxe pick them up
nicely as "slaves". We just need to make sure that the variables are set
first, for the variables -> ConPlatformDxe -> ConSplitterDxe dependency
chain.

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Olivier Martin <Olivier.martin@arm.com>
git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@16912 6f19259b-4bc3-4df7-8a09-765794883524