Re: [edk2-devel] [PATCH EDK2 v1 1/1] MdeModulePkg: Modify PCD default value

["Ni, Ray" <ray.ni@intel.com>]

Wenyi,
Can you explain a bit more about "if 52 bit physical address need to be supported, page size should also be set to 64KB alignment"?

Can the platform DSC override this value instead of changing the default value in MdeModulePkg.dec which impacts all platforms?

Thanks,
Ray

-----Original Message-----
From: devel@edk2.groups.io <devel@edk2.groups.io> On Behalf Of wenyi,xie via groups.io
Sent: Thursday, July 15, 2021 8:25 PM
To: devel@edk2.groups.io; Wang, Jian J <jian.j.wang@intel.com>; Wu, Hao A <hao.a.wu@intel.com>
Cc: songdongkuang@huawei.com; wanghuiqiang@huawei.com; xiewenyi2@huawei.com
Subject: [edk2-devel] [PATCH EDK2 v1 1/1] MdeModulePkg: Modify PCD default value

From: "wenyi.xie" <xiewenyi2@huawei.com>

The default value of PcdSrIovSystemPageSize is 0x1, it means the memory BAR is 4KB alignment. When page size of OS is set to 64KB, as the resource partitions are different between OS and BIOS, it will cause pcie failture. And if 52 bit physical address need to be supported, page size should also be set to 64KB alignment.
So modify the default vaule of PcdSrIovSystemPageSize to 0x10 can meet the requirement above. And even if the OS is 4KB alignment, new value of PCD is compatible for this situation.

Cc: Jian J Wang <jian.j.wang@intel.com>
Cc: Hao A Wu <hao.a.wu@intel.com>
Signed-off-by: Wenyi Xie <xiewenyi2@huawei.com>
---
 MdeModulePkg/MdeModulePkg.dec | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/MdeModulePkg/MdeModulePkg.dec b/MdeModulePkg/MdeModulePkg.dec index ad84421cf3..426ea1b6cc 100644
--- a/MdeModulePkg/MdeModulePkg.dec
+++ b/MdeModulePkg/MdeModulePkg.dec
@@ -1853,7 +1853,7 @@
   #  BIT0 set indicates 4KB alignment<BR>
   #  BIT1 set indicates 8KB alignment<BR>
   # @Prompt SRIOV system page size.
-  gEfiMdeModulePkgTokenSpaceGuid.PcdSrIovSystemPageSize|0x1|UINT32|0x10000047
+
+ gEfiMdeModulePkgTokenSpaceGuid.PcdSrIovSystemPageSize|0x10|UINT32|0x10
+ 000047
 
   ## SMBIOS version.
   # @Prompt SMBIOS version.
--
2.20.1.windows.1