[PATCH v2 2/2] ArmPkg/PlatformBootManagerLib: reject 'default' parity and stop bit count

["Ard Biesheuvel" <ard.biesheuvel@arm.com>]

In the ArmPkg version of PlatformBootManagerLib, we construct a
serial device path based on the default settings for baud rate,
parity and the number of stop bits, to ensure that a serial console
is available even on the very first boot.

This assumes that PcdUartDefaultParity or PcdUartDefaultStopBits are
not set to '0', meaning 'the default', as there is no default for
these when constructing a device path.

So add a couple of STATIC_ASSERT()s to make sure that we catch this
condition, since it otherwise ignores the bogus device path silently,
which is rather tedious to debug,.

Signed-off-by: Ard Biesheuvel <ard.biesheuvel@arm.com>
---
 ArmPkg/Library/PlatformBootManagerLib/PlatformBm.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.c b/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.c
index f713605c02b2..3411219fbfdb 100644
--- a/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.c
+++ b/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.c
@@ -585,6 +585,10 @@ PlatformBootManagerBeforeConsole (
   //
   STATIC_ASSERT (FixedPcdGet8 (PcdDefaultTerminalType) == 4,
     "PcdDefaultTerminalType must be TTYTERM");
+  STATIC_ASSERT (FixedPcdGet8 (PcdUartDefaultParity) != 0,
+    "PcdUartDefaultParity must be set to an actual value, not 'default'");
+  STATIC_ASSERT (FixedPcdGet8 (PcdUartDefaultStopBits) != 0,
+    "PcdUartDefaultStopBits must be set to an actual value, not 'default'");
 
   CopyGuid (&mSerialConsole.TermType.Guid, &gEfiTtyTermGuid);
 
-- 
2.17.1