Re: [PATCH v3 07/15] ArmVirtPkg: Early serial port initialisation

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

(+ Julien)

On 6/24/20 3:34 PM, Sami Mujawar wrote:
> Initialise serial port early so that the platform
> memory map can be logged.
> 
> Signed-off-by: Sami Mujawar <sami.mujawar@arm.com>
> ---
>   ArmVirtPkg/PrePi/PrePi.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/ArmVirtPkg/PrePi/PrePi.c b/ArmVirtPkg/PrePi/PrePi.c
> index 4f0c3f98bad63d0682cccd76a0a062d1fd4f46ab..5e144f4bdefb810708238097a3373f11d150bfe5 100755
> --- a/ArmVirtPkg/PrePi/PrePi.c
> +++ b/ArmVirtPkg/PrePi/PrePi.c
> @@ -1,6 +1,6 @@
>   /** @file
>   *
> -*  Copyright (c) 2011-2014, ARM Limited. All rights reserved.
> +*  Copyright (c) 2011-2020, ARM Limited. All rights reserved.
>   *
>   *  SPDX-License-Identifier: BSD-2-Clause-Patent
>   *
> @@ -60,16 +60,16 @@ PrePiMain (
>     //
>     InvalidateDataCacheRange((VOID *)(UINTN)PcdGet64 (PcdFdBaseAddress), PcdGet32 (PcdFdSize));
>   
> -  // Initialize MMU and Memory HOBs (Resource Descriptor HOBs)
> -  Status = MemoryPeim (UefiMemoryBase, FixedPcdGet32 (PcdSystemMemoryUefiRegionSize));
> -  ASSERT_EFI_ERROR (Status);
> -
>     // Initialize the Serial Port
>     SerialPortInitialize ();
>     CharCount = AsciiSPrint (Buffer,sizeof (Buffer),"UEFI firmware (version %s built at %a on %a)\n\r",
>       (CHAR16*)PcdGetPtr(PcdFirmwareVersionString), __TIME__, __DATE__);
>     SerialPortWrite ((UINT8 *) Buffer, CharCount);
>   
> +  // Initialize MMU and Memory HOBs (Resource Descriptor HOBs)
> +  Status = MemoryPeim (UefiMemoryBase, FixedPcdGet32 (PcdSystemMemoryUefiRegionSize));
> +  ASSERT_EFI_ERROR (Status);
> +
>     // Create the Stacks HOB (reserve the memory for all stacks)
>     StacksSize = PcdGet32 (PcdCPUCorePrimaryStackSize);
>     BuildStackHob (StacksBase, StacksSize);
> 

We need to check whether this works on Xen - I don't remember whether we 
use some kind of cache coherent shared memory ring there for the serial 
console that only works if the MMU and caches are enabled. Julien?