On Sat, Aug 5, 2017 at 11:08 AM, Mark Kettenis mark.kettenis@xs4all.nl wrote:
From: Rob Clark robdclark@gmail.com Date: Sat, 5 Aug 2017 10:35:08 -0400
On Sat, Aug 5, 2017 at 10:28 AM, Mark Kettenis mark.kettenis@xs4all.nl wrote:
Date: Sat, 5 Aug 2017 16:01:51 +0200 (CEST) From: Mark Kettenis mark.kettenis@xs4all.nl
Unfortunately something in this patch series breaks things for me on a Banana Pi:
And according to git bisect:
4e3e748a50fc3f43e20c7ff407184596d7c9a589 is the first bad commit commit 4e3e748a50fc3f43e20c7ff407184596d7c9a589 Author: Peter Jones pjones@redhat.com Date: Wed Jun 21 16:39:02 2017 -0400
efi: add some more device path structures Signed-off-by: Peter Jones <pjones@redhat.com> Signed-off-by: Rob Clark <robdclark@gmail.com>hmm, odd.. it is only adding some #define's and structs that are not used until a later commit..
although it does also make 'struct efi_device_path_mac_addr' __packed, which it should have been before. Is this an armv7? I wonder if we have some troubles with unaligned accesses on armv7 that we don't have on aarch64 (or maybe compiler isn't turning access to device-path nodes into byte accesses if it can't do unaligned accesses. (The node in the device-path structure are byte-packed.)
This is indeed armv7.
addr2line the faulting address I guess should confirm that. If this is the issue, it's going to be a bit sad since we'll have to do a lot of copying back/forth of efi_device_path ptrs to aligned addresses :-/
Sadly that's not going to help you:
$ arm-none-eabi-addr2line -e u-boot 7ef8d878 ??:0
I suppose it is faulting somewhere in BOOTARM.EFI,
Anyway, removing __packed from struct efi_device_path_file_path makes me boot again with a tree checked out out with that commit.
Our bootloader code doesn't explicitly enable alignment faults. But of course the UEFI standard says that for AArc32 platforms:
- Unaligned access should be enabled if supported; Alignment faults are enabled otherwise.
So the efi_loader code has to align things properly I fear.
Ok, so I have an idea for a reasonably (imho) sane way forward:
struct efi_device_path_mac_addr { struct efi_device_path dp; struct efi_mac_addr mac; u8 if_type; #ifdef BROKEN_UNALIGNED u8 pad[3]; #endif } __packed;
We'll just define BROKEN_UNALIGNED for armv7 and any other arch's that can't handle unaligned accesses. Technically it is a bit outside the way things are *supposed* to work according to my understanding of the UEFI spec. But all the code I've seen that parses the device-paths honors the length field in the efi_device_path header to find the start of the next node in the path. I can't guarantee that you'll be able to boot windows from u-boot (but I guess that isn't what most people care about ;-)), but it at least won't be more broken than it was before on these archs.
It will take a bit of extra special handling for efi_device_path_file_path (which is variable length) but with my patchset that only gets constructed in one place, so it isn't so bad.
BR, -R