virtio: add virtiofs #86768

fkokosinski · 2025-03-07T12:29:58Z

This PR:

adds virtiofs functions and required fuse structures
implements zephyr filesystem operations for virtiofs
adds virtiofs sample that presents use of this filesystem

~~Note that this draft PR uses the VIRTIO PCI driver implemented in #83892, and is meant to showcase how the VIRTIO PCI driver can be used with Zephyr.~~

cfriedt · 2025-04-07T14:35:42Z

@fkokosinski -

Looks very good so far.

Is it possible to separate the virtiofs and fuse contributions into separate commits? I think they can be used independently - e.g. network based FUSE.

I was initially searching for the separation between host and device roles under drivers/virtio, but now it's a bit more clear that drivers/virtio is mainly for common components and host and device drivers will live under their respective subsystems.

Maybe slightly different naming would make it easier to differentiate which is the host driver and which is the device between e.g. with virtiofs.c and virtiofs_zvfs.c, maybe virtiofs_host.c and virtiofs_device.c. Naming things is hard though, so it's maybe good to discuss. Additionally, different subsystems have different naming conventions for things, but it would be nice to have some cross-subsystem naming.

Given that it might be hard to identify all of the different virtio drivers that will eventually be scattered throughout Zephyr, and which might do the host side vs device side, I would also like to see a new section in the documentation.

maybe place things under doc/hardware/virtualization
good high-level topics
- Overview
- Concepts (an SVG diagram would go a long way here)
- Common VirtIO libraries
- Host-side VirtIO drivers
- Device-side VirtIO drivers
- VirtIO Samples

Happy to help move this along any way I can.

fkokosinski · 2025-04-23T13:34:13Z

Hey @cfriedt, thanks for your comment!

I believe all of your remarks have been addressed in the recent push (here and in the VIRTIO PCI API PR).

aescolar · 2025-06-03T15:50:06Z

include/zephyr/fs/fuse.h

+/*
+ * Copyright (c) 2025 Antmicro <www.antmicro.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0


The original header seems to be BSD licensed,
https://github.com/torvalds/linux/blob/master/include/uapi/linux/fuse.h
shouldn't this reflect the original copyright and license?

We moved the code that was based on thi sheader to a separate file (fuse_abi.h), with the original BSD license

Shouldn't it be possible to install this header with a kernel headers package of some kind?

Why are we even duplicating it inside of the Zephyr repo?

Unfortunately, there are some issues with including externally supplied headers:

Layout of FUSE structures is not stable and was changing in the past (e.g. struct sizes were changed regularly and in some early commits even struct names and field names were sometimes altered) and presumably will also change in the future. This may cause all sorts of problems if a subset of this header used by Zephyr is modified. The virtiofsd itself doesn't use this header, instead it uses its own definitions (https://gitlab.com/virtio-fs/virtiofsd/-/blob/main/src/fuse.rs) and as of now its already a few versions behind the fuse.h from Linux

Zephyr allows building on platforms different than Linux and this header won't be present on those. For example, up until recently (QEMU 8.0), virtiofsd was supporting macOS hosts (in QEMU 8.0 implementation was changed to rust based one and non-linux support was dropped), so including header from Linux would artificially limit this use case.

doc/hardware/virtualization/virtio.rst

include/zephyr/fs/virtiofs.h

samples/subsys/fs/virtiofs/README.rst

subsys/fs/fuse/CMakeLists.txt

de-nordic · 2025-06-03T15:48:13Z

include/zephyr/fs/fuse.h

+#include <stdint.h>
+#include <zephyr/kernel.h>
+
+/* adapted from Linux: include/uapi/linux/fuse.h */


Doesn't this require some license/copyrights from the original file? @kartben

We moved the code that was based on thi sheader to a separate file (fuse_abi.h), with the original BSD license

de-nordic · 2025-06-03T15:48:30Z

include/zephyr/fs/fuse.h

+
+struct fuse_out_header {
+	uint32_t len;
+	int32_t	error;


de-nordic · 2025-06-03T16:28:02Z

subsys/fs/virtiofs/virtiofs_zfs.c

+#ifdef CONFIG_VIRTIOFS_VIRTIOFSD_UNLINK_QUIRK
+	struct fuse_entry_out lookup_ret;
+	/*
+	 * Even if unlink doesn't take nodeid as a param it still fails with EIO if the node


We've reworked this function a bit, but yes - it was -EIO; changed to that.

fkokosinski · 2025-06-30T10:04:15Z

Licenses make ci red

@de-nordic right. I've tagged this PR with the TSC label so that it is brought to the TSC's attention, which I believe is the required next step for this PR.

In the meantime, could you please revisit this PR and let me know if there's anything else that still needs to be addressed here?

nashif · 2025-06-30T12:48:38Z

@de-nordic right. I've tagged this PR with the TSC label so that it is brought to the TSC's attention, which I believe is the required next step for this PR.

is this about bsd licensed files?

fkokosinski · 2025-06-30T13:05:16Z

@de-nordic right. I've tagged this PR with the TSC label so that it is brought to the TSC's attention, which I believe is the required next step for this PR.

is this about bsd licensed files?

Yes, it's about this single BSD-licensed header file, which specifies the FUSE ABI: https://github.com/zephyrproject-rtos/zephyr/blob/b6cb351e5418d635341b72606e45c73c4a3aa851/subsys/fs/fuse_client/fuse_abi.h.

nashif · 2025-07-01T11:22:47Z

Yes, it's about this single BSD-licensed header file, which specifies the FUSE ABI: b6cb351/subsys/fs/fuse_client/fuse_abi.h.

isnt this targeting native simulator only?

fkokosinski · 2025-07-01T11:29:03Z

Yes, it's about this single BSD-licensed header file, which specifies the FUSE ABI: b6cb351/subsys/fs/fuse_client/fuse_abi.h.

isnt this targeting native simulator only?

We’re using this with QEMU. We’re showcasing this in the subsys/fs/virtiofs sample this PR is adding: https://github.com/zephyrproject-rtos/zephyr/tree/b6cb351e5418d635341b72606e45c73c4a3aa851/samples/subsys/fs/virtiofs

nashif · 2025-07-01T11:39:30Z

We’re using this with QEMU. We’re showcasing this in the subsys/fs/virtiofs sample this PR is adding: b6cb351/samples/subsys/fs/virtiofs

ok, thanks.

nashif · 2025-07-02T11:53:51Z

subsys/fs/fuse_client/fuse_abi.h

@@ -0,0 +1,269 @@
+/* SPDX-License-Identifier: BSD-2-Clause */


originally in Linux this file is licensed:

SPDX-License-Identifier: ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause)

looks like you are picking BSD-2 here, the question if this is something we can actually do, because here you are basically changing the license and dropping GPL and only the copyright holder should be able to do that. Need to check if we should keep the original license as is and add some clarification.

for example, mbed-tls is SPDX-License-Identifier: Apache-2.0 OR GPL-2.0-or-later and we are fine with that, we do not modify the SPDX and do not remove GPL-2.0....

Right. I've changed the fuse_abi.h license so that the original identifier is preserved.

fkokosinski · 2025-07-03T09:11:22Z

The following changes were made:

doc/LICENSING.rst now references the subsys/fs/fuse_client/fuse_abi.h.h file
subsys/fs/fuse_client/fuse_abi.h now directly specifies under which license it is used while preserving the original SPDX license identifier

This commit adds fuse structures, requests and functions to fill them Signed-off-by: Jakub Michalski <jmichalski@antmicro.com>

This commit adds virtiofs functions implementing fuse operations required to enable zephyr filesystem support Signed-off-by: Jakub Michalski <jmichalski@antmicro.com>

This commit implements zephyr filesystem operations for virtiofs Signed-off-by: Jakub Michalski <jmichalski@antmicro.com> Signed-off-by: Filip Kokosinski <fkokosinski@antmicro.com>

This commit adds virtiofs sample that presents use of this filesystem Signed-off-by: Jakub Michalski <jmichalski@antmicro.com> Signed-off-by: Filip Kokosinski <fkokosinski@antmicro.com>

This commit adds sections to the virtio docs with the currently supported transfer methods, drivers and samples Signed-off-by: Jakub Michalski <jmichalski@antmicro.com>

fkokosinski · 2025-07-07T09:17:06Z

Rebased due to conflicts after #92682 was merged.

sonarqubecloud · 2025-07-07T09:38:26Z

Quality Gate passed

Issues
12 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud

This was referenced Mar 3, 2025

[RFC] VIRTIO support in Zephyr #86561

Open

drivers: add API for VIRTIO devices and add VIRTIO PCI driver #83892

Merged

fkokosinski force-pushed the 66707-virtiofs branch 3 times, most recently from ba271da to d24c129 Compare March 7, 2025 13:48

fkokosinski force-pushed the 66707-virtiofs branch 2 times, most recently from 05ddf1c to 59c7537 Compare April 23, 2025 10:47

jmichalski-ant force-pushed the 66707-virtiofs branch 2 times, most recently from 9049399 to 1a0b654 Compare June 3, 2025 09:21

fkokosinski marked this pull request as ready for review June 3, 2025 10:27

fkokosinski changed the title ~~[DRAFT] virtio: add virtiofs~~ virtio: add virtiofs Jun 3, 2025

github-actions bot added area: Samples Samples area: File System labels Jun 3, 2025

github-actions bot requested review from de-nordic, kartben, Laczen and nashif June 3, 2025 10:27

github-actions bot assigned de-nordic Jun 3, 2025

de-nordic requested a review from aescolar June 3, 2025 11:37

aescolar reviewed Jun 3, 2025

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fkokosinski force-pushed the 66707-virtiofs branch from 1a0b654 to 59c7537 Compare June 13, 2025 08:45

github-actions bot added area: VIRTIO area: Process labels Jun 13, 2025

github-actions bot requested review from kgugala, MaureenHelm, stephanosio and tgorochowik June 13, 2025 08:46

aescolar added Override Required and removed Override Required labels Jun 30, 2025

nashif reviewed Jul 2, 2025

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fkokosinski dismissed stale reviews from cfriedt, kgugala, and aescolar via 3807ec3 July 2, 2025 12:48

fkokosinski force-pushed the 66707-virtiofs branch from b6cb351 to 3807ec3 Compare July 2, 2025 12:48

aescolar previously approved these changes Jul 2, 2025

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fkokosinski dismissed aescolar’s stale review via 0a828f7 July 3, 2025 09:06

fkokosinski force-pushed the 66707-virtiofs branch from 3807ec3 to 0a828f7 Compare July 3, 2025 09:06

cfriedt previously approved these changes Jul 3, 2025

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jmichalski-ant added 5 commits July 7, 2025 09:40

fs: add fuse primitives

910d44d

This commit adds fuse structures, requests and functions to fill them Signed-off-by: Jakub Michalski <jmichalski@antmicro.com>

fs: add virtiofs operations

5a23b2d

This commit adds virtiofs functions implementing fuse operations required to enable zephyr filesystem support Signed-off-by: Jakub Michalski <jmichalski@antmicro.com>

fs: implement zephyr fs api for virtiofs

3fb1603

This commit implements zephyr filesystem operations for virtiofs Signed-off-by: Jakub Michalski <jmichalski@antmicro.com> Signed-off-by: Filip Kokosinski <fkokosinski@antmicro.com>

fs: virtiofs: add virtiofs sample

b599a36

This commit adds virtiofs sample that presents use of this filesystem Signed-off-by: Jakub Michalski <jmichalski@antmicro.com> Signed-off-by: Filip Kokosinski <fkokosinski@antmicro.com>

docs: virtio: add section about available drivers and samples

d535276

This commit adds sections to the virtio docs with the currently supported transfer methods, drivers and samples Signed-off-by: Jakub Michalski <jmichalski@antmicro.com>

fkokosinski dismissed cfriedt’s stale review via d535276 July 7, 2025 09:12

fkokosinski force-pushed the 66707-virtiofs branch from 0a828f7 to d535276 Compare July 7, 2025 09:12

aescolar approved these changes Jul 7, 2025

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cfriedt approved these changes Jul 8, 2025

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nashif moved this from Todo to Done in TSC Attention Needed Jul 9, 2025

		@@ -0,0 +1,269 @@
		/* SPDX-License-Identifier: BSD-2-Clause */

virtio: add virtiofs #86768

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virtio: add virtiofs #86768

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