On Wed, 2014-07-16 at 16:53 +0100, Mark Rutland wrote: > On Wed, Jul 16, 2014 at 03:51:37PM +0100, Mark Salter wrote: > > On Tue, 2014-07-15 at 12:58 +0200, Ard Biesheuvel wrote: > > > After the EFI stub has done its business, it jumps into the kernel by > > > branching > > > to offset #0 of the loaded Image, which is where it expects to find the > > > header > > > containing a 'branch to stext' instruction. > > > > > > However, the header is not covered by any PE/COFF section, so the header > > > may > > > not actually be loaded at the expected offset. So instead, jump to 'stext' > > > directly, which is at the base of the PE/COFF .text section, by supplying > > > a > > > symbol 'stext_offset' to efi-entry.o which contains the relative offset of > > > stext into the Image. Also replace other open coded calculations of the > > > same > > > value with a reference to 'stext_offset' > > > > Have you actually seen a situation where the header isn't there? > > Isn't the kernel header actually part of the pe/coff file and > > firmware loads the whole file into RAM? > > From my understanding of Ard's earlier comments, this part isn't > guaranteed per the UEFI spec. > > I would rather we weren't relying on implementation details. >
Could be. I didn't see anything about it in the UEFI spec, but I probably wasn't exhaustive in my search. In any case, there's at least one other place broken if the kernel header isn't included in the loaded image. -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
