Interesting, I was just fixing logic that was already there. If it is really desired to follow https://www.kernel.org/doc/Documentation/arm64/booting.txt BdsLinuxLoader.c should be simplified greatly.
I think what my code will do is effectively move the system memory base to the lowest available memory address after PcdSystemMemoryBase. It looks like the Linux will ignore any memory regions below where the kernel is. If memory at low addresses is reserved by UEFI from use by the OS for whatever reason, the PcdSystemMemoryBase is not the base of memory that the OS would see. I assume this must have been the intent of the original developer of BdsLinuxLoader.c. Garrett Kirkendall [Description: Description: Description: purple] SMTS Firmware Engineer | AMD Technology & Engineering 7171 Southwest Parkway, Austin, TX 78735 USA [Description: Description: Description: image004] facebook<https://www.facebook.com/AMD> | amd.com<http://www.amd.com/> From: Olivier Martin [mailto:olivier.mar...@arm.com] Sent: Monday, February 24, 2014 10:50 AM To: edk2-devel@lists.sourceforge.net Subject: Re: [edk2] [PATCH] ArmPkg/Library/BdsLib: Fix Linux kernel load when 1st call to BdsLoadImage fails. Garrett, I pushed your fix about 'adding EfiReservedMemoryType regions to FDT'. But there is a misinterpretation of the Linux Booting protocol into the other part of your patch. The Linux Boot protocol says: "The image must be placed at the specified offset (currently 0x80000) from the start of the system RAM and called there. The start of the system RAM must be aligned to 2MB." Source: https://www.kernel.org/doc/Documentation/arm64/booting.txt Your patch tries to load Linux kernel on any 2MB boundary if it fails at 'SystemMemoryBase + 0x80000' - which is wrong. If it fails at 'SystemMemoryBase + 0x80000' then it should just abort Linux loading. Thanks, Olivier From: Kirkendall, Garrett [mailto:garrett.kirkend...@amd.com] Sent: 17 February 2014 17:04 To: edk2-devel@lists.sourceforge.net<mailto:edk2-devel@lists.sourceforge.net> Subject: [edk2] [PATCH] ArmPkg/Library/BdsLib: Fix Linux kernel load when 1st call to BdsLoadImage fails. Dear ArmPkg maintainers, Please consider the attached patch that handles loading the Linux kernel when the first call to BdsLoadImage fails. Also, it makes sure that the PSCI disabled processor holding pen can be allocated when loading the kernel image. Garrett Kirkendall [Description: Description: Description: purple] SMTS Firmware Engineer | AMD Technology & Engineering 7171 Southwest Parkway, Austin, TX 78735 USA [Description: Description: Description: image004] facebook<https://www.facebook.com/AMD> | amd.com<http://www.amd.com/>
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