Hi Casey, Ilias,
On 7/28/2026 5:51 PM, Casey Connolly wrote:
On 28/07/2026 13:44, Balaji Selvanathan wrote:
Hi Ilias,
On 7/27/2026 9:57 PM, Balaji Selvanathan wrote:
Hi Ilias,
On 7/27/2026 6:11 PM, Ilias Apalodimas wrote:
On Mon, 27 Jul 2026 at 13:00, Balaji Selvanathan
<[email protected]> wrote:
Hi Ilias, Casey,
On 7/24/2026 12:37 AM, Casey Connolly wrote:
On 23/07/2026 18:43, Balaji Selvanathan wrote:
Hi Casey,
On 7/22/2026 8:19 PM, Casey Connolly wrote:
Hi Balaji,
On 22/07/2026 11:23, Balaji Selvanathan wrote:
Hi Casey,
On 7/18/2026 4:19 PM, Casey Connolly wrote:
On 7/17/26 18:16, Balaji Selvanathan wrote:
Hi Casey, Ilias, Simon,
On 5/26/2026 7:05 PM, Casey Connolly wrote:
Hi Balaji,
On 25/05/2026 13:24, Balaji Selvanathan wrote:
Hi Ilias,
On 5/23/2026 6:23 PM, Ilias Apalodimas wrote:
[...]
To support multi-image RAW capsules, we would need to:
1. Enhance mkeficapsule to create multi-image capsules?
There's an equivalent tool in EDKII that can produce a
capsule
with
multiple payloads. There were also patches posted for
mkeficapsule,
but need some minor tweaks to merge them
Can you please point me those patches? I did a search
myself, but
couldnt find those patches.
https://lore.kernel.org/u-boot/20240419065542.1160527-1-
[email protected]/
This patch you mentioned here can create capsule with only one
payload;
means for multiple binaries we need to create multiple
capsules. I
have
also asked the person who made this series to respin, but
havent
heard
back from him.
From a quick look it seems like it would be fairly
straightforward to
extend mkeficapsule to support multiple images, the capsule
header
has
an item_offset_list[] array with offsets to each image, today
we just
write 1 but it shouldn't be too much of a challenge to put a
loop in
here and extend the argument parsing.
Given that we a) already use raw capsules and b) they are
part of the
EFI spec, I'm gonna try and save us all some time and just
put my
foot
down here. A single raw EFI capsule file can already support
updating
multiple images, U-Boot already has all of the machinery for
it with
the
exception of mkeficapsule but I expect that's something you can
tackle.
The upside to this is that you will be able to build capsule
files
for
updating xbl/tz/hyp/aop that can be consumed by U-Boot and edk2!
Thanks for the detailed feedback.
We agree — we'll drop the FIT capsule approach and move
forward with
RAW capsules.
Here's the plan:
1. mkeficapsule tool: Extend Sughosh's multi-payload capsule
series
[1] to support generating multi-image capsules from a config
file, so we can build a single capsule covering all the
partitions
we need to update.
2. U-Boot (Qualcomm): Today the Qualcomm capsule update code only
supports a single firmware image (U-Boot itself) via a
single-entry fw_images[] array. We'll move to a SoC-
specific,
multi- entry fw_images[] array (defined per board, e.g.
board/qualcomm/<board>/fw_images.c), so a single capsule
update
flow can cover multiple firmware components — each with its own
ESRT entry and FMP image_index — instead of just U-Boot.
No need for this, just build fw_images[] on the fly derived
from the
partition table on the board, with an entry for each partition
that
can be updated. You just need to add a map from partition label to
fw_name string, starting with the xbl/uefi/boot partitions we
already
handle.
The entire point of having logic here was to avoid per-board
stuff, if
you're thinking "ah I'll do this per-board" you should immediately
wonder "but can we do it dynamically instead?".
Thanks,
Casey
Hi Casey, Ilias,
Thanks for the pointer — agreed, building fw_images[]
dynamically
from
the partition table is the right call, avoids per-target code
entirely.
Can I talk to a human instead of an LLM please?
Plan:
- Keep a fixed table mapping "partition label → fw_name + a
fixed
image index", this mapping going to be a superset list for all
the Boot
FW images supported in different Qualcomm targets.
This reads vaguely like a rephrasing of what I proposed, not
clear if
you really understand it though.
Sample table:
┌──────────────────┬───────────────┬───────┬────────────────────────┐
│ part_base_name │ fw_name │ index
│ guid
(fixed) │
├──────────────────|───────────────|───────-|
───────────────────────- |
│ xbl │ QCOM_XBL │ 1
│ QCOM_XBL_GUID │
│ ubootspl │ QCOM_UBOOTSPL│ 2 │
QCOM_UBOOTSPL_GUID │
│ uboot │ QCOM_UBOOT │ 3
│ QCOM_UBOOT_GUID │
└──────────────────┴───────────────┴───────┴────────────────────────┘
Target-1 supports xbl and Target-2 supports ubootspl.
- At boot, scan the partition table against this table. Only
partitions actually present on that target get an fw_images[]/
ESRT entry
— nothing hardcoded per target.
- The image index for each partition type stays fixed and
published,
so whoever builds a capsule (mkeficapsule) always knows which
index to
target, regardless of what's discovered at runtime.
One wrinkle I want to flag: today's SetImage() path assumes
dfu_alt_num = image_index - 1, i.e. it picks the Nth entry in
dfu_alt_info purely by
position. If a partition from the middle of the table is
missing on a
given target, everything after it would shift by one position
and the
wrong
partition would get flashed — silently. Since I'd rather
not touch
that logic in common code, my plan is to keep every fixed index's
position in
dfu_alt_info stable by inserting a placeholder (U-Boot's
existing
virt
DFU backend, which just no-ops) wherever a partition is absent,
so the
position
math stays correct for everything after it. The missing
partition
itself simply won't have an fw_images[]/ESRT entry, so a capsule
can't
target it
anyway — it'd get rejected before reaching DFU.
Skipping past this noise... Ilias probably knows better here but
yes the
way dfu_alt_num is derived from ImageIndex does impose a
limitation here
currently where we need to ensure the indexes always start at 1 and
count up.
That being said, it's already quite complicated to have to
maintain a
database of the indices for each board, and even more complicated
when
we have boards that may or may not be using U-Boot SPL (for
example).
Having fixed ImageIndex values for each image would then seem to
make
the most sense as we could just use fwu to set dfu_alt_num (or
another
platform specific mechanism), however the EFI spec is clear that the
ImageIndex of EFI_FIRMWARE_IMAGE_DESCRIPTOR must be <=
DescriptorCount
as returned by fmp->GetImageInfo(), so we would need to also have
dummy
entries in the fw_images[] array so it doesn't really solve our
problem.
https://uefi.org/specs/
UEFI/2.9_A/23_Firmware_Update_and_Reporting.html
Currently, other than for setting dfu_alt_num, the only other place
where the image index needs to match is in efi_fmp_find() which was
added by [1] seemingly to prevent an incorrect image index in the
/capsule/ file causing dfu_alt_num to be set wrong resulting in the
wrong partition being flashed. In other words, we should be able
to find
a way to safely remove this check.
But alas, it seems like we are stuck with fmp->SetImage() being
called
with the image index from the capsule file per the spec, and it
is the
only way to identify the target partition without doing other hacks.
I'd like to get some feedback from Ilias on this, since adding dummy
entries really doesn't feel like an acceptable approach to me.
The only
alternatives I can think of also don't seem great... Either:
1. Sidestep the EFI spec by either caching data in the call to
GetImageInfo() or by assuming that the void *image pointer
immediately
follows the efi_firmware_management_capsule_image_header (this is
true
for us today but would be a fragile assumption to make).
2. Use the internal image index (looked up via the image name and
type_id) as the index when calling fmp->set_image() - going
against the
spec.
It's not really clear to me what purpose the ImageIndex property
serves,
since GetImageInfo() is meant to match on the ImageTypeId anyway, I
assume it relates somehow to the fact that there can be multiple
instances of the firmware management protocol, but in U-Boot we only
have one.
I think the other way forward would be to use the only included
escape
hatch in the UEFI spec with a custom GUID in the capsule header
capsule_guid field which would let us have a custom mechanism
which in
our case could just be a soft-fork of the existing spec with minor
changes so we can just remove/ignore the UpdateImageIndex field
in the
capsule. Maybe this would be the most correct solution?
Hopefully Ilias has some time to chime in on this, I'm sure we
can find
a way to go about this that doesn't involve exposing dummy data.
Thanks,
// Casey
I feel we are complicating it by trying to go for dynamic fw_images.
Rather than introducing a solution that diverges from the UEFI
specification, shall we use a board-specific static fw_images[]
Well, the solution I proposed at the end very much doesn't diverge
from
the spec, that was kinda the point.
definition. This approach is simpler, remains spec-compliant, and
other
Simpler for you to implement or simpler to maintain? I think that's
quite debatable...
vendors (like NXP, TI) have also implemented static fw_images (in
board/
nxp, board/ti).
The decision not to do this for mach-snapdragon was quite intentional
and was the motivator behind dynamic generation of image GUIDs:
https://lore.kernel.org/u-boot/20240830-b4-dynamic-uuid-
[email protected]/
The image index issue was always bound to come up, and it's absolutely
something we should be solving and not just sidestepping. We already
support dynamic fw_images[] anyway and it's already being used by some
devices, so we need to maintain the existing support regardless.
As I understand it, Qualcomm also intend to support multiple boot
media
(UFS, eMMC, SPI flash) with a single U-Boot binary, so to some extent
this array must be dynamic. And since at boot time we have all the
info
we need to generate fw_images, keeping a static list per-board is at
best lazy and at worst will just make things even more complicated
when
we suddenly want to support configurations with/without OP-TEE and
with/without SPL.
So unless I'm missing something here I think there's a strong case
here
to add support for ignoring the capsule provided image index, but
we'll
see what Ilias has to say when he's back from vacation.
Okay Casey.
Hi Ilias,
Request your input on this.
So the problem you are trying to fix here, is that you have boards
with multiple configurations, that their image index might change, but
you want to update them with a single capsule right?
If that's the case, we can have a board specific function that does
nothing by default, but on the qualcomm case, re-arranges the capsule
image indexes *after* the capsule authentication has passed. I think
this still violates the EFI spec, but I am ok with it.
Cheers
/Ilias
Hi Ilias,
Thanks for the input. Just to make sure we're on the same page:
Our understanding is that we'd add a board-specific hook (default
no-op, so other vendors are unaffected) that runs after the capsule
signature is verified but before dfu_alt_num is
derived from image_index. On Qualcomm boards, this hook would look
at the partitions actually present at boot and remap the capsule's
(fixed, published) image_index to whatever position that image
actually occupies in dfu_alt_info on that specific target — rather
than assuming a fixed 1:1 mapping between image_index and position.
To be clear on scope: we're not ignoring the image_index value
itself — it's still read from the capsule and used as-is to look up
which firmware component (xbl/uboot/etc.) is being
no, the entire point is that the image index is bunk, why are you
feeding these emails through an LLM?
targeted. What we're overriding is the spec's assumption that this
index also encodes position, i.e. that dfu_alt_num = image_index - 1
and that image_index stays within descriptor_count.
the spec's assumption????? this has nothing to do with the spec
Since our FMP descriptor list is built dynamically per-board, a
fixed global index can exceed the descriptor count on boards missing
some partitions, so we remap it to the correct DFU
no
position ourselves instead.
Is that a correct read of what you had in mind?
please use plain text formatting for emails.
Regards,
Balaji
If the above assumption is correct, then we will have following problems,
During authentication, U-Boot performs anti-rollback checks.
As part of this flow, the Image Index is converted to an Image GUID
using fw_images[].
Since the capsule Image Index does not match the fw_images[] Image Index
at this stage, the anti-rollback logic may resolve the wrong GUID or
fail to find a matching entry in fw_images[].
I'd like to understand from Ilias why we need to authenticate the
firmware first before adjusting the image index, I'd hope we could avoid
that? Unless changing the index would invalidate the checksum
The image is authenticated inside of fmp->SetImage() at which point we
don't have the image type ID or name so it's too late at that point. We
would need to adjust it earlier.
perhaps we could go about it another way, what if we add a dfu_alt_num
field to efi_fw_image (and add a flag to efi_capsule_update_info to
indicate if the new field is valid), then in efi_capsule.c just before
we call efi_fmp_find() we can call a new weak function that would adjust
the image index of the matching efi_fw_image so it matches whatever is
in the capsule. Then we don't have to care what it is since we can use
the right dfu_alt_num field anyway.
Maybe this could just all be done in efi_capsule.c and not even need a
platform hook, either gated behind a config option or just behind the
new efi_fw_image.dfu_alt_num field being used.
I worry that's too much of a workaround that might cause issues down the
line but I'm not really familiar enough with this to be sure.
Casey,
We have checked and this approach seems to be fine. In this approach
though, it comes back to the issue we saw earlier: the image index (from
the capsule) could be > descriptor count.
If this is fine, then we can proceed with this approach. Atleast we
won't be creating dummy dfu strings.
Ilias,
Would like to hear your view on this, so we are all on the same page.
Regards,
Balaji
Regards,
Balaji
Regards,
Balaji
Regards,
Balaji
[1]: 7cf06f09cc51 ("capsule: Put a check for image index before the
update")
Let me know if this approach sounds reasonable.
Thanks,
Balaji
Will send an updated series once the mkeficapsule and qcom
capsule
update changes are in shape.
[1] https://lore.kernel.org/u-boot/20240419065542.1160527-1-
[email protected]/
Regards,
Balaji
Kind regards,
