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

["Leif Lindholm" <leif@nuviainc.com>]

On Mon, May 18, 2020 at 19:11:48 +0200, Ard Biesheuvel wrote:
> 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 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>

Reviewed-by: Leif Lindholm <leif@nuviainc.com>

> ---
>  ArmPkg/Library/PlatformBootManagerLib/PlatformBm.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.c b/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.c
> index e6e788e0f107..a030d510aa62 100644
> --- a/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.c
> +++ b/ArmPkg/Library/PlatformBootManagerLib/PlatformBm.c
> @@ -583,6 +583,8 @@ PlatformBootManagerBeforeConsole (
>    //
>    // Add the hardcoded serial console device path to ConIn, ConOut, ErrOut.
>    //
> +  ASSERT (FixedPcdGet8 (PcdUartDefaultParity) > 0);
> +  ASSERT (FixedPcdGet8 (PcdUartDefaultStopBits) > 0);
>    ASSERT (FixedPcdGet8 (PcdDefaultTerminalType) == 4);
>    CopyGuid (&mSerialConsole.TermType.Guid, &gEfiTtyTermGuid);
>  
> -- 
> 2.17.1
>