[PATCH v3 0/6] fs: Add 9P filesystem support over virtio

[Kuan-Wei Chiu <visitorckw@gmail.com>]

Add 9P network filesystem support to U-Boot.

It allows U-Boot to directly mount host directories in virtualization
environments via virtio. This is useful for loading kernel and
initramfs images directly from the host into the VM during development
and testing without having to rebuild disk images or set up a TFTP
server.

The functionality has been verified on qemu arm64 by successfully
loading a Linux kernel image and an initramfs image via 9P, and booting
to the Linux shell.

To test with QEMU:
  -fsdev local,id=fsdev0,path=/path/to/host/dir,security_model=none \
  -device virtio-9p-device,fsdev=fsdev0,mount_tag=rootfs

U-Boot usage:
  => virtio scan
  => ls 9p rootfs /
  => ls 9p 0 /
  => ls 9p - /
  => load 9p rootfs $kernel_addr_r /Image
  => load 9p rootfs $ramdisk_addr_r /initramfs.cpio
  => booti $kernel_addr_r $ramdisk_addr_r:$filesize $fdtcontroladdr

Changes in v3:
- Return received byte length from virtio_9p_request() and check it
  against the reply header size in p9_request().
- Call virtio_del_vqs() before virtio_reset() in virtio_9p_remove().
- Use double backticks for literal text in 9p.rst.
- Assert expected error strings in test_9p.py negative test cases.
- Add doc/develop/pytest/test_9p.rst.

Changes in v2:
- Introduce DM UCLASS_9P and dm_p9_ops for transport devices.
- Support selecting devices by mount tag, sequence index, or default.
- Integrate 9p into disk/part.c and generic VFS null_dev_desc handling.
- Consistently use 9P2000.L naming across subjects, code, and Kconfig.
- Add kerneldoc comments and separate filesystem header.
- Add timeout handling, feature negotiation, and remove callback.
- Add 9P documentation.
- Add automated pytest and enable in qemu_arm64_defconfig.
- Fix error checking, bounds checks, and memory leaks.

Kuan-Wei Chiu (6):
  net: 9p: Add 9P2000.L protocol support
  fs: 9p: Add 9P filesystem support
  virtio: 9p: Add 9P transport driver
  doc: 9p: Add 9P filesystem documentation
  test: 9p: Add test for 9P filesystem
  MAINTAINERS: Add entry for 9PFS

 MAINTAINERS                    |  12 +
 configs/qemu_arm64_defconfig   |   3 +
 disk/part.c                    |  16 ++
 doc/develop/pytest/test_9p.rst |  10 +
 doc/usage/filesystems/9p.rst   |  55 +++++
 doc/usage/index.rst            |   1 +
 drivers/virtio/Kconfig         |   7 +
 drivers/virtio/Makefile        |   1 +
 drivers/virtio/virtio-uclass.c |   1 +
 drivers/virtio/virtio_9p.c     | 120 ++++++++++
 fs/9p/9p.c                     | 185 +++++++++++++++
 fs/9p/Kconfig                  |   8 +
 fs/9p/Makefile                 |   5 +
 fs/Kconfig                     |   2 +
 fs/Makefile                    |   1 +
 fs/fs.c                        |  25 ++
 include/9p.h                   | 203 ++++++++++++++++
 include/9pfs.h                 |  60 +++++
 include/dm/uclass-id.h         |   1 +
 include/fs.h                   |   1 +
 include/virtio.h               |  12 +-
 net/9p/Kconfig                 |   5 +
 net/9p/Makefile                |   5 +
 net/9p/client.c                | 415 +++++++++++++++++++++++++++++++++
 net/Kconfig                    |   2 +
 net/Makefile                   |   1 +
 test/py/tests/test_9p.py       |  82 +++++++
 27 files changed, 1238 insertions(+), 1 deletion(-)
 create mode 100644 doc/develop/pytest/test_9p.rst
 create mode 100644 doc/usage/filesystems/9p.rst
 create mode 100644 drivers/virtio/virtio_9p.c
 create mode 100644 fs/9p/9p.c
 create mode 100644 fs/9p/Kconfig
 create mode 100644 fs/9p/Makefile
 create mode 100644 include/9p.h
 create mode 100644 include/9pfs.h
 create mode 100644 net/9p/Kconfig
 create mode 100644 net/9p/Makefile
 create mode 100644 net/9p/client.c
 create mode 100644 test/py/tests/test_9p.py

-- 
2.56.0.rc1.310.g51773c2048-goog