On Tue, Jun 16, 2015 at 05:19:29PM +0100, Michael Brown wrote: > On 15/06/15 22:43, Linn Crosetto wrote: > >Michael Brown <mbrown@...> writes: > >>The kernel will align itself to the nearest boundary specified by the > >>kernel_alignment field in the bzImage header. If the kernel is loaded > >>to an address which is not sufficiently aligned, it will therefore use > >>memory beyond that indicated solely by the init_size field. > >> > >>The PE/COFF headers now include a .bss section to describe the > >>requirements of the init_size field, but do not currently expose the > >>alignment requirement. Consequently, a kernel loaded via the PE entry > >>point may still end up overwriting unexpected areas of memory. > >> > >>Fix by exposing the desired alignment via the SectionAlignment field > >>in the PE/COFF headers. Despite its name, this field provides an > >>overall alignment requirement for the loaded file. (Naturally, the > >>FileAlignment field describes the alignment for individual sections.) > >> > >>There is no way in the PE/COFF headers to express the concept of > >>min_alignment; we therefore do not expose the minimum (as opposed to > >>preferred) alignment. > > > ><snip> > > > >There may be a problem with this change. The specification says that the > >SizeOfImage field must be a multiple of SectionAlignment. That was the case > >when SectionAlignment was 0x20, but now that it is so large it would > >require quite an increase in the last section to comply. A kernel I am > >looking at now has: > > > >Alignment of sections: 0x1000000 > >Size of image: 0x105a000 > > Any suggested solution? I have been reverting this patch as a workaround. The fields need to be changed, but I am not that familiar with the code. Maybe there is a way to use a heuristic to calculate the best values based on init_sz? -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
