Integration for GrubCC and SystemdBoot by Johan-Liebert1 · Pull Request #1113 · coreos/bootupd

Johan-Liebert1 · 2026-06-12T08:38:13Z

Add Bootloader enum

Now that we are going to support multiple bootloaders, we need a way to
keep track of which one we're operating on

For bootupd generate-update-metadata we now generate metadata for all
found bootloaders. The final json will look like

{
  "timestamp": "2026-06-10T09:52:58.107743026Z",
  "version": "grub-cc-1:2.12-59.fc45,grub2-1:2.12-58.fc44,shim-16.1-5",
  "versions": [
    { "name": "grub-cc", "rpm_evr": "1:2.12-59.fc45" },
    { "name": "grub2", "rpm_evr": "1:2.12-58.fc44" },
    { "name": "shim", "rpm_evr": "16.1-5" }
  ]
}

This allows us to have multiple bootloaders in a single image and
install/update based on preference.

During install/update, we check to bootloader and filter out any and all
entries from the update metadata that do not match or are not required
for the bootloader

For grub we store the statefile in /sysroot/boot/bootupd.json. For
grub-cc, and in future systemd-boot, we won't have a /boot, so we now
store the state pre bootloader.

Grub2: Statefile is still in /sysroot/boot/bootupd.json
GrubCC: Statefile is stored in all the ESPs

Store the sysroot_path in StateLockGuard which we require for mounting
the ESP. Also, mount the ESP at /boot which is what the BLS spec suggest

See: #1080

gemini-code-assist

Code Review

This pull request introduces support for multiple bootloaders, specifically adding a new GrubCC option alongside the default Grub. It updates the saved state, component installation, update, and status mechanisms to dynamically detect and filter metadata based on the active bootloader, including handling state files stored in the ESP for GrubCC. The review feedback identifies a potential mount leak where the was_mounted flag is not reset upon unmounting, several instances of unnecessary double referencing, and opportunities to make the code more idiomatic by simplifying OnceLock usage and removing redundant iterator adapters.

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Now that we are going to support multiple bootloaders, we need a way to keep track of which one we're operating on Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Generate metadata for only a particular bootloader, either Grub or GrubCC Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Add `is_bootloader_supported` function to figure out if bootloader is supported by the component or not. Skip installs and metadata generation for the component if it does not support the bootloader Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

For grub we store the statefile in `/sysroot/boot/bootupd.json`. For grub-cc, and in future systemd-boot, we won't have a `/boot`, so we now store the state pre bootloader. Grub2: Statefile is still in `/sysroot/boot/bootupd.json` GrubCC: Statefile is stored in all the ESPs Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Store the sysroot_path in StateLockGuard which we require for mounting the ESP. Also, prevent mounting ESP at a tempdir, instead just mount it at `/boot` which is what the BLS spec suggest Fix issue with composefs systems where lsblk would fail to find the backing device for "/" due to it being mounted as a virtual filesystem. Instead we now use `/sysroot` or `/boot` to find the baking device Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

For `bootupd generate-update-metadata` we now generate metadata for all found bootloaders. The final json will look like ```json { "timestamp": "2026-06-10T09:52:58.107743026Z", "version": "grub-cc-1:2.12-59.fc45,grub2-1:2.12-58.fc44,shim-16.1-5", "versions": [ { "name": "grub-cc", "rpm_evr": "1:2.12-59.fc45" }, { "name": "grub2", "rpm_evr": "1:2.12-58.fc44" }, { "name": "shim", "rpm_evr": "16.1-5" } ] } ``` This allows us to have multiple bootloaders in a single image and install/update based on preference. During install/update, we check to bootloader and filter out any and all entries from the update metadata that do not match or are not required for the bootloader Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Only allow Grub as the bootloader for powerpc and s390x Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Johan-Liebert1 · 2026-07-02T06:31:51Z

I've tested SystemdBoot and GrubCC installation with bootc and it seems to work fine. Having this test in the CI would be helpful but we have a circular dependency between bootc and this PR

This works exactly like GrubCC We expect systemd-boot efi to be in `/usr/lib/efi/systemd-boot/<evr>/fedora/grubx64.cc` Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

We don't have e2e upgrade tests for now, but we can atleast test if the installations are working well Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

We generate the final filetree from `/usr/lib/efi` which worked well with only one bootloader, but now that we have three which are stored in the following places Grub2 - /usr/lib/efi/grub2/<evr>/EFI/fedora/grubx64.efi GrubCC - /usr/lib/efi/grub-cc/<evr>/EFI/fedora/grubx64.efi SystemdBoot - /usr/lib/efi/systemd-boot/<evr>/EFI/fedora/grubx64.efi The problem arises as all the distinct efi binaries have the same name (grubx64.efi - due to the particular name being baked into shim), we cannot blindly create a filesystem tree out of this as later values will override the previous ones. To mitigate this, introduce a param `skip_dirs` which will filter directories not required for the bootloader being installed Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

A utility cfg macro defined in build.rs so that we can deny EFI only bootloaders - GrubCC and SystemdBoot, on non-EFI systems at compile time Also, only allow setting default bootloaders for EFI systems Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Use this enum in match statements so that if we add a new component in future, we'll get compile time errors in places where we need to handle the new component. This also gets rid of some hardcoded strings Also remove `#[default]` from Bootloader enum. Having a "default" in the enum doesn't make sense as we never construct this enum Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Johan-Liebert1 · 2026-07-08T13:12:53Z

A lot of changes here. I'll test it out in fcos as an override

cgwalters · 2026-07-08T21:12:55Z

+    grubName="grubaa64.efi"
+fi
+
+cp /usr/lib/systemd/boot/efi/systemd-boot*.efi "/usr/lib/efi/systemd-boot/${evr}/EFI/$ID/$grubName"


Hmmm, is this really required? I guess it must be - it's us taking over bootctl install and bootctl update.

That feels...unnecessary?

Now that I spend a bit of time on this, is this case actually "install systemd-boot pretending to be grub" so it gets chainloaded by shim? That looks like what this is.

That feels like a clearly distinct case of things here and really worth clearly documenting.

OK right, and we're doing the same with grub-cc?

Hmmm, I guess it's kind of an assumption woven into things here that we're using shim, which is probably the right one by default, but I think we do ultimately need to handle non-shim cases too.

I guess this isn't blocking per se, but we should have a note about this.

Now that I spend a bit of time on this, is this case actually "install systemd-boot pretending to be grub" so it gets chainloaded by shim? That looks like what this is.

yes, that's what it is. We will probably hardlink the actual systemd-boot binary at /usr/lib/efi/systemd-boot/** so that all bootloader live in the same place

OK right, and we're doing the same with grub-cc?

yes

but I think we do ultimately need to handle non-shim cases too

We do. On a call with @travier we decided to handle that case later

The name of the EFI binary loaded by shim is hardcoded in shim: https://src.fedoraproject.org/rpms/shim-unsigned-x64/blob/rawhide/f/shim-unsigned-x64.spec#_154

There are options to change it but they have a lot of downsides: #1080 (comment)

Pretending to be grub$arch.efi is apparently the simplest option.

We settled (at least for now) on leaving standalone systemd-boot (or potentially standalone grub-cc) support to systemd's bootctl as we don't need all the complexity from bootupd for those cases: #1080 (comment)

Rolv-Apneseth

Couple of questions and suggestions but wow, this is cool

Rolv-Apneseth · 2026-07-09T12:24:45Z

+        ;;
+    grub)
+        EFI_DIR_NAME=grub2
+        ;;


Should we have a failure for the default case?

Rolv-Apneseth · 2026-07-09T12:24:58Z

 use std::io::prelude::*;
 use std::path::Path;

+fn parse_statefile(statusf: cap_std::fs::File) -> Result<Option<SavedState>> {


WDYT about doing something like:

fn parse_statefile(statusf: cap_std::fs::File) -> Result<SavedState> { let mut bufr = BufReader::new(statusf); let mut s = String::new(); bufr.read_to_string(&mut s)?; let state: serde_json::Result<SavedState> = serde_json::from_str(s.as_str()); match state { Ok(s) => Ok(s), Err(orig_err) => { let legacy_state: serde_json::Result<crate::model_legacy::SavedState01> = serde_json::from_str(s.as_str()); legacy_state .map(crate::model_legacy::SavedState01::upconvert) .map_err(|_| orig_err.into()) } } }

And at the call sites:

root.open_optional(&path) .map_err(Into::into) .and_then(|o| o.map(parse_statefile).transpose())

Rolv-Apneseth · 2026-07-09T12:25:08Z

+                    // According to BLS, the ESP should be mounted at /boot or /boot/efi
+                    // which the following method already checks
+                    let mounted = efi
+                        .ensure_mounted_esp(Path::new("/"), Path::new(&esp.path()))


Should this be using root_path in the case of an install to e.g. /var/mnt?

Rolv-Apneseth · 2026-07-09T12:25:29Z

+        root_path: impl AsRef<Path>,
+        bootloader: Bootloader,
+    ) -> Result<()> {
+        let saved_state = SavedState::load_from_disk(&root_path, Some(bootloader))?;


load_from_disk calls device.find_first_colocated_esp() for grub-cc and systemd-boot - do we need to handle the case where no ESP is found?

Rolv-Apneseth · 2026-07-09T12:26:18Z

+            // Do the sync before unmount
+            fsfreeze_thaw_cycle(dir.reopen_as_ownedfd()?)?;
+            drop(dir);
+            efi.unmount().context("unmount after update")?;


Is it intended that this unmounts even when was_mounted = true due to how Efi::unmount sets was_mounted = false?

Rolv-Apneseth · 2026-07-09T12:27:09Z

+            } else {
+                Bootloader::Grub
+            }
+        }


Suggested change

}

Some(info) => match info.to_lowercase() {

i if i.contains("grub cc") => Bootloader::GrubCC,

i if i.contains("systemd-boot") => Bootloader::Systemd,

_ => Bootloader::Grub,

},

Rolv-Apneseth · 2026-07-09T12:27:21Z

+                //
+                //  We can't install GrubCC for BIOS as it's not supported
+                //  So we just default to installing GrubCC
+                (Some(_), Some(eb)) => eb,


Suggested change

(Some(_), Some(eb)) => eb,

(_, Some(eb)) => eb,

Rolv-Apneseth · 2026-07-09T12:28:02Z

+
+    /// Returns bootloaders are available for install
+    #[cfg(efi_arch)]
+    pub(crate) fn num_bootloader_available(&self) -> Vec<Bootloader> {


I think this should be renamed since it doesn't actually return a number

Rolv-Apneseth · 2026-07-09T12:28:15Z

+    #[cfg(efi_arch)]
+    pub(crate) fn bootloader_available(&mut self, bootloader: Bootloader) -> bool {
+        self.version
+            .split(",")
+            .any(|v| v.starts_with(bootloader.efi_component_name()))
+    }


Suggested change

#[cfg(efi_arch)]

pub(crate) fn bootloader_available(&mut self, bootloader: Bootloader) -> bool {

self.version

.split(",")

.any(|v| v.starts_with(bootloader.efi_component_name()))

}

#[cfg(efi_arch)]

pub(crate) fn is_bootloader_available(&self, bootloader: Bootloader) -> bool {

self.version

.split(',')

.any(|v| v.starts_with(bootloader.efi_component_name()))

}

Rolv-Apneseth · 2026-07-09T12:29:17Z

+
+. /etc/os-release
+
+# Create the expected directory structure at /usr/lib/efi/grub-cc/<evr>/EFI/fedora/


It looks like this was meant to be the systemd-boot path

gemini-code-assist Bot reviewed Jun 12, 2026

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Comment thread src/efi.rs

Comment thread src/efi.rs Outdated

Comment thread src/backend/statefile.rs Outdated

Comment thread src/backend/statefile.rs

Comment thread src/backend/statefile.rs

Comment thread src/bootloader.rs

Comment thread src/model.rs

Johan-Liebert1 force-pushed the grub-cc branch 2 times, most recently from 2ffcc16 to e8da148 Compare June 12, 2026 08:56

Johan-Liebert1 marked this pull request as draft June 12, 2026 09:31

openshift-ci Bot added the do-not-merge/work-in-progress label Jun 12, 2026

Johan-Liebert1 force-pushed the grub-cc branch 5 times, most recently from 77321d0 to fb028b8 Compare June 14, 2026 03:19

Johan-Liebert1 marked this pull request as ready for review June 15, 2026 05:10

openshift-ci Bot removed the do-not-merge/work-in-progress label Jun 15, 2026

Johan-Liebert1 force-pushed the grub-cc branch 2 times, most recently from aa72462 to e7bf29d Compare June 15, 2026 05:35

Johan-Liebert1 requested review from cgwalters and travier June 15, 2026 05:49

cgwalters reviewed Jun 17, 2026

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Comment thread src/cli/bootupd.rs Outdated

travier mentioned this pull request Jun 20, 2026

feat(uki): sealed image builds secureblue/secureblue#2348

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Johan-Liebert1 requested a review from cgwalters June 22, 2026 07:10

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openshift-ci Bot added the needs-rebase label Jun 23, 2026

Johan-Liebert1 added 9 commits June 23, 2026 09:37

Add Bootloader enum

b05cb68

Now that we are going to support multiple bootloaders, we need a way to keep track of which one we're operating on Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

efi: Filter components by bootloader

1b9b19e

Generate metadata for only a particular bootloader, either Grub or GrubCC Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Handle installs for bootloaders

e613340

Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

efi: Do not unmount if mountpoint was already mounted

3a68754

Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Fix builds for powerpc and s390x

98b6302

Only allow Grub as the bootloader for powerpc and s390x Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Johan-Liebert1 force-pushed the grub-cc branch 4 times, most recently from 1c646b3 to 1106373 Compare June 25, 2026 10:26

Johan-Liebert1 changed the title ~~Integration for GrubCC~~ Integration for GrubCC and SystemdBoot Jun 25, 2026

Johan-Liebert1 mentioned this pull request Jun 27, 2026

Support uki key in BLSConfig bootc-dev/bootc#2269

Merged

Johan-Liebert1 force-pushed the grub-cc branch 6 times, most recently from 3a39aed to 4dd892b Compare June 29, 2026 11:15

Johan-Liebert1 requested a review from cgwalters June 29, 2026 11:45

Johan-Liebert1 force-pushed the grub-cc branch from 4dd892b to 62ec2d4 Compare July 2, 2026 06:47

bootloader: Add SystemdBoot enum variant

99e9487

This works exactly like GrubCC We expect systemd-boot efi to be in `/usr/lib/efi/systemd-boot/<evr>/fedora/grubx64.cc` Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Johan-Liebert1 force-pushed the grub-cc branch from 62ec2d4 to 0d4bb9e Compare July 2, 2026 07:06

Johan-Liebert1 added 3 commits July 2, 2026 13:11

ci: Add tests for grub-cc and systemd-boot

2da4853

We don't have e2e upgrade tests for now, but we can atleast test if the installations are working well Signed-off-by: Pragyan Poudyal <pragyanpoudyal41999@gmail.com>

Johan-Liebert1 force-pushed the grub-cc branch from 0d4bb9e to bce8404 Compare July 2, 2026 07:41

travier mentioned this pull request Jul 2, 2026

Building ISOs from sealed bootable containers osbuild/image-builder#2455

Open

cgwalters approved these changes Jul 7, 2026

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Comment thread src/bootupd.rs Outdated

Comment thread src/bootloader.rs

cgwalters mentioned this pull request Jul 7, 2026

bootupd: make new packagesystem, using a file, no rpm -q #1121

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Johan-Liebert1 force-pushed the grub-cc branch from a55c226 to 7a8cae6 Compare July 8, 2026 09:06

Johan-Liebert1 force-pushed the grub-cc branch from 7a8cae6 to 2225384 Compare July 8, 2026 12:57

cgwalters reviewed Jul 8, 2026

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Rolv-Apneseth reviewed Jul 9, 2026

View reviewed changes

-        }
+        Some(info) => match info.to_lowercase() {
+            i if i.contains("grub cc") => Bootloader::GrubCC,
+            i if i.contains("systemd-boot") => Bootloader::Systemd,
+            _ => Bootloader::Grub,
+        },


		. /etc/os-release

		# Create the expected directory structure at /usr/lib/efi/grub-cc/<evr>/EFI/fedora/

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Johan-Liebert1 commented Jun 12, 2026 •

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