Hi,
attached patch reworks the payload handling with CBFS (ie. selfboot). We use a bounce buffer (both in CBFS and older) to keep coreboot running while allowing the payload to use the same memory region, and this is a tricky part of our code.
Assumptions in the code are: The bounce buffer is at least 2x coreboot_ram size (lb_end - lb_start), with the first half being the shadow region that the payload's data lives in (exactly the bytes that cover the area of coreboot_ram), while the second half exists to host a copy of coreboot while copying.
The change leads to the following behaviour: At least 2x coreboot_ram size is looked for.
The area before the bounce buffer is assumed to be reasonably free (but this isn't validated)
Payload segments that conflict with coreboot_ram are loaded to the bounce buffer, probably using the memory before it, and filling up more than coreboot_ram bytes there
Right after copying, the "out of area" bytes are copied to their final location (around coreboot_ram).
I want to revisit the prefix/suffix calculation, as I'm not 100% sure that it's doing the right thing (those copy operations should copy _exactly_ the necessary set of bytes, nothing more), review is welcome (look for "prefix" and "suffix" in selfboot.c)
The code is runtime tested on qemu-x86 (after cranking up the STACK_SIZE to >16kb, so lzma could run), with the following scenarios:
RAMBASE = 0x4000, payload starting at 0x00100000 (no collision between coreboot_ram and payload)
RAMBASE = 0x00100000, payload starting at 0x00100000 (RAMBASE below or at payload starting address, this worked before)
RAMBASE = 0x00101000, payload starting at 0x00100000 (RAMBASE above payload starting address, this fails without this patch. AMD boards were notorious with that one)
Pending the review of the prefix/suffix calculations (by me and hopefully others), this is
Signed-off-by: Patrick Georgi patrick.georgi@coresystems.de
Once this is in, there are no CBFS issues that I know of, and hence I propose to eliminate non-CBFS support in the tree soonish after that patch is in. I have some older patch for this, but it will likely not apply anymore, but I can update it.
Opinions?
Regards, Patrick