On Tue, Feb 23, 2016 at 11:58:05AM +0000, Mark Rutland wrote: > On Mon, Feb 22, 2016 at 05:58:19PM -0800, David Daney wrote: > > From: Ard Biesheuvel <ard.biesheuvel@xxxxxxxxxx> > > > > There are two problems with the UEFI stub DT memory node removal > > routine: > > - it deletes nodes as it traverses the tree, which happens to work > > but is not supported, as deletion invalidates the node iterator; > > - deleting memory nodes entirely may discard annotations in the form > > of additional properties on the nodes. > > > > Since the discovery of DT memory nodes occurs strictly before the > > UEFI init sequence, we can simply clear the memblock memory table > > before parsing the UEFI memory map. This way, it is no longer > > necessary to remove the nodes, so we can remove that logic from the > > stub as well. > > This is a little bit scary, but I guess this works. > > My only concern is that when we get kexec, a subsequent kernel must also > have EFI memory map support, or things go bad for the next EFI-aware > kernel after that (as things like the runtime services may have been > corrupted by the kernel in the middle). It's difficult to fix the > general case later. > > A different option would be to support status="disabled" for the memory > nodes, and ignore these in early_init_dt_scan_memory. That way a kernel > cannot use memory without first having parsed the EFI memory map, and we > can still get NUMA info from the disabled nodes. So in that case, the middle, non-EFI kernel would fail to boot? Realistically, once you've kexec'd a non-EFI payload, I don't think you can rely on the EFI state remaining intact for future EFI applications. Is this really something we should be trying to police in the kernel? Will -- 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
