On Mon, Feb 27, 2023 at 10:53:45AM -0500, Stefan Hajnoczi wrote: > On Fri, Feb 24, 2023 at 03:37:51PM +0100, David Heidelberg wrote: > > From: Stefan Hajnoczi <stefanha@xxxxxxxxxx> > > > > Make it possible to boot directly from a virtiofs file system with tag > > 'myfs' using the following kernel parameters: > > > > rootfstype=virtiofs root=myfs rw > > > > Booting directly from virtiofs makes it possible to use a directory on > > the host as the root file system. This is convenient for testing and > > situations where manipulating disk image files is cumbersome. > > > > Reviewed-by: Helen Koike <helen.koike@xxxxxxxxxxxxx> > > Signed-off-by: Stefan Hajnoczi <stefanha@xxxxxxxxxx> > > Signed-off-by: David Heidelberg <david@xxxxxxx> > > --- > > v2: added Reviewed-by and CCed everyone interested. > > > > We have used this option in Mesa3D CI for testing crosvm for > > more than one years and it's proven to work reliably. > > > > We are working on effort to removing custom patches to be able to do > > automated apply and test of patches from any tree. > > > > https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/.gitlab-ci/crosvm-runner.sh#L85 > > init/do_mounts.c | 10 ++++++++++ > > 1 file changed, 10 insertions(+) > > Vivek, do you remember where we ended up with boot from virtiofs? I > thought a different solution was merged some time ago. We merged a patch from Christoph Hellwig to support this. commit f9259be6a9e7c22d92e5a5000913147ae17e8321 Author: Christoph Hellwig <hch@xxxxxx> Date: Wed Jul 14 16:23:20 2021 -0400 init: allow mounting arbitrary non-blockdevice filesystems as root Now one should be able to mount virtiofs using following syntax. "root=myfs rootfstype=virtiofs rw" IIUC, this patch should not be required anymore. Thanks Vivek > > There is documentation from the virtiofs community here: > https://virtio-fs.gitlab.io/howto-boot.html > > Stefan > > > > > diff --git a/init/do_mounts.c b/init/do_mounts.c > > index 811e94daf0a8..11c11abe23d7 100644 > > --- a/init/do_mounts.c > > +++ b/init/do_mounts.c > > @@ -578,6 +578,16 @@ void __init mount_root(void) > > printk(KERN_ERR "VFS: Unable to mount root fs via SMB.\n"); > > return; > > } > > +#endif > > +#ifdef CONFIG_VIRTIO_FS > > + if (root_fs_names && !strcmp(root_fs_names, "virtiofs")) { > > + if (!do_mount_root(root_device_name, "virtiofs", > > + root_mountflags, root_mount_data)) > > + return; > > + > > + panic("VFS: Unable to mount root fs \"%s\" from virtiofs", > > + root_device_name); > > + } > > #endif > > if (ROOT_DEV == 0 && root_device_name && root_fs_names) { > > if (mount_nodev_root() == 0) > > -- > > 2.39.1 > >
