Scott Duplichan wrote:
From: Tobias Diedrich ]Linux also needs the MMCONF area to be reserved either in E820 or ]as an ACPI motherboard resource or it will not enable MMCONFIG ]and the extended pcie configuration area will be unaccessible: ] ]This patch adds the IORESOURCE_RESERVE flag to the APIC and MMCONF ]resource flags to do this. ]I also added a new resource for the mapped bios rom area just below 4GB. ]I'm not sure if the choice for the index parameter of new_resource() ]is correct though. ]Note that the bios rom decode is enabled in ]src/southbridge/via/vt8237r/vt8237r_early_smbus.c ]for the whole 4MB area (even though the comment says 1MB).
Thank you Tobias. To be even more conservative, the upper 5 MB of the first 4GB can be reserved for flash memory. This is because many LPC flash chips place the jedec ID register of the boot device at address ffbc0000.
I think that probably doesn't apply here, since the LPC flash shouldn't get chip-select outside the selected area. However src/southbridge/via/vt8237r/bootblock.c (which I had missed because I got my board to work without touching this file) says its actually 8MB big for VT8237A and VT8237S.