Hi Ard and Gerd,

Thanks,
Chao

On 2024/3/15 17:54, Chao Li wrote:

Hi Ard,

On 2024/3/15 17:51, Ard Biesheuvel wrote:

On Fri, 15 Mar 2024 at 10:49, Chao Li <lichao@loongson.cn> wrote:

Hi Gerd,


Thanks,
Chao
On 2024/3/15 17:33, Gerd Hoffmann wrote:

On Mon, Mar 11, 2024 at 05:39:02PM +0800, Chao Li wrote:

Add a serial port hook library in LoongArchVirt named
Fdt16550SerialProtHookLib, this library is referenced from ArmVirtPkg.

LoongArch QEMU virtual machine uses register of LOONGARCH_CSR_KS1 to
transfer serial port base addres from the PEI phase to the DXE phase.

Why use LOONGARCH_CSR_KS1?  Can't you simply set PcdSerialRegisterBase?

The LoongArch QEMU PEI stage runs on flash and does not allow set PCD operations(memory have not enabled), so the address can only be transferred through a SAVE register.

Then maybe use a HOB instead?

Ha, I forgot this way, let's me try.

I remember, before committing the first version, I tried to usb the HOB in this library, but if the HOB library is referenced, the UefiDevicePathLibDevicePathProtocol.inf and UefiLib.inf will be cycle consumed, I rememberd the UefiDevicePathLibDevicePathProtocol.inf included a constructor that will cause the cycle comsumed.

So, I think it is a better choice for this library to use register KCS1.

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