Hi Gerd,

Thanks,
Chao

On 2024/3/20 18:16, Gerd Hoffmann wrote:

On Mon, Mar 18, 2024 at 04:28:17PM +0100, Gerd Hoffmann wrote:

On Sat, Mar 16, 2024 at 10:17:00AM +0800, lixianglai wrote:

Hi Gerd:

On Mon, Mar 11, 2024 at 02:39:31AM -0700, Chao Li wrote:

This library for PEI phase, and obtains the QemuFwCfg base address by
directly parsing the FDT, reads and writes the data in QemuFwCfg by
operating on the QemuFwCfg base address.
 create mode 100644 OvmfPkg/LoongArchVirt/Library/FdtQemuFwCfgLib/FdtQemuFwCfgPeiLib.c
 create mode 100644 OvmfPkg/LoongArchVirt/Library/FdtQemuFwCfgLib/FdtQemuFwCfgPeiLib.inf
 create mode 100644 OvmfPkg/LoongArchVirt/Library/FdtQemuFwCfgLib/QemuFwCfgLibInternal.h
 create mode 100644 OvmfPkg/LoongArchVirt/Library/FdtQemuFwCfgLib/QemuFwCfgPei.c

Is there anything LoongArch-specific in there?

No,The main function of this lib library is to obtain the fwcfg base address by parsing fdt in the pei stage,
 and provide access to fwcfg through mmio mode,
 the difference between it and the existing library is that the fwcfg base address is not hard-coded in the compilation stage,
 and is accessed through mmio rather than io port.

That would be the case for risc-v and aarch64 too, although I think they
don't need fw_cfg right now (they get all info needed via fdt).

Oops, I was wrong, we have OvmfPkg/Library/QemuFwCfgLib/QemuFwCfgLibMmio.inf

QemuFwCfgLibMmio.inf is looks like a DXE stage library, while this patch is the PEI stage library we are dicussing.

I have tow plans:

Plan A: Keep this library under LoongArchQemuVirt.

Plan B: Create a new INF named QemuFwCfgPeiLibMmio.inf under OvmfPkg/Library/QemuFwCfgLib/, which will obtain the resources from FDT, and store them in the HOB or dynamic PCD.

Which one do you like? I'm leaning toward B because more people will be served if it's under OvmfPkg/Library.


take care,
  Gerd

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