| Message ID | 208f1fceffce2feaf7c900b29e326b967dce7762.1585661532.git.qemu_oss@crudebyte.com |
|---|---|
| State | New |
| Headers | show |
| Series | qemu-options.hx: 9p: clarify -virtfs vs. -fsdev | expand |
On Tue, 31 Mar 2020 15:23:38 +0200 Christian Schoenebeck <qemu_oss@crudebyte.com> wrote: > The docs are ambiguous about the difference (or actually their > equality) between options '-virtfs' vs. '-fsdev'. So clarify that > '-virtfs' is actually just a convenience shortcut for its > generalized form '-fsdev' in conjunction with '-device virtio-9p-pci'. > > And as we're at it, also be a bit more descriptive what 9pfs is > actually used for. > > Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com> > --- > qemu-options.hx | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/qemu-options.hx b/qemu-options.hx > index 962a5ebaa6..fd3830c6cd 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -1542,9 +1542,17 @@ SRST > ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly]`` > \ > ``-virtfs synth,mount_tag=mount_tag`` > - Define a new filesystem device and expose it to the guest using a > - virtio-9p-device. The general form of a Virtual File system > - pass-through options are: > + Define a new virtual filesystem device and expose it to the guest using > + a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain > + directory on host is made directly accessible by guest as a pass-through > + file system by using the 9P network protocol for communication between > + host and guests, if desired even accessible, shared by several guests > + simultaniously. > + > + Note that ``-virtfs`` is actually just a convenience shortcut for its > + generalized form ``-fsdev -device virtio-9p-pci``. Huh. This prompted me to try this on s390, and it actually creates a virtio-9p-pci device there as well, not a virtio-9p-ccw device. A bit surprising; but I don't see 9p used much (if at all) on s390 anyway. > + > + The general form of pass-through file system options are: > > ``local`` > Accesses to the filesystem are done by QEMU. Good to see this spelled out: Acked-by: Cornelia Huck <cohuck@redhat.com>
On Dienstag, 31. März 2020 17:27:27 CEST Cornelia Huck wrote: > > diff --git a/qemu-options.hx b/qemu-options.hx > > index 962a5ebaa6..fd3830c6cd 100644 > > --- a/qemu-options.hx > > +++ b/qemu-options.hx > > @@ -1542,9 +1542,17 @@ SRST > > > > ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag > > [,writeout=writeout][,readonly]``> > > \ > > > > ``-virtfs synth,mount_tag=mount_tag`` > > > > - Define a new filesystem device and expose it to the guest using a > > - virtio-9p-device. The general form of a Virtual File system > > - pass-through options are: > > + Define a new virtual filesystem device and expose it to the guest > > using + a virtio-9p-device (a.k.a. 9pfs), which essentially means that > > a certain + directory on host is made directly accessible by guest as > > a pass-through + file system by using the 9P network protocol for > > communication between + host and guests, if desired even accessible, > > shared by several guests + simultaniously. > > + > > + Note that ``-virtfs`` is actually just a convenience shortcut for its > > + generalized form ``-fsdev -device virtio-9p-pci``. > > Huh. This prompted me to try this on s390, and it actually creates a > virtio-9p-pci device there as well, not a virtio-9p-ccw device. A bit > surprising; but I don't see 9p used much (if at all) on s390 anyway. Yeah, "virtio-9p-pci" is currently hard coded in softmmu/vl.c [line 3352]: https://github.com/qemu/qemu/blob/17083d6d1e0635371418c26b613a6fa68d392f49/softmmu/vl.c#L3352 > > + > > > > + The general form of pass-through file system options are: > > ``local`` > > > > Accesses to the filesystem are done by QEMU. > > Good to see this spelled out: > > Acked-by: Cornelia Huck <cohuck@redhat.com> Best regards, Christian Schoenebeck
Christian Schoenebeck <qemu_oss@crudebyte.com> writes: > On Dienstag, 31. März 2020 17:27:27 CEST Cornelia Huck wrote: >> > diff --git a/qemu-options.hx b/qemu-options.hx >> > index 962a5ebaa6..fd3830c6cd 100644 >> > --- a/qemu-options.hx >> > +++ b/qemu-options.hx >> > @@ -1542,9 +1542,17 @@ SRST >> > >> > ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag >> > [,writeout=writeout][,readonly]``> >> > \ >> > >> > ``-virtfs synth,mount_tag=mount_tag`` >> > >> > - Define a new filesystem device and expose it to the guest using a >> > - virtio-9p-device. The general form of a Virtual File system >> > - pass-through options are: >> > + Define a new virtual filesystem device and expose it to the guest >> > using + a virtio-9p-device (a.k.a. 9pfs), which essentially means that >> > a certain + directory on host is made directly accessible by guest as >> > a pass-through + file system by using the 9P network protocol for >> > communication between + host and guests, if desired even accessible, >> > shared by several guests + simultaniously. >> > + >> > + Note that ``-virtfs`` is actually just a convenience shortcut for its >> > + generalized form ``-fsdev -device virtio-9p-pci``. >> >> Huh. This prompted me to try this on s390, and it actually creates a >> virtio-9p-pci device there as well, not a virtio-9p-ccw device. A bit >> surprising; but I don't see 9p used much (if at all) on s390 anyway. > > Yeah, "virtio-9p-pci" is currently hard coded in softmmu/vl.c [line 3352]: > https://github.com/qemu/qemu/blob/17083d6d1e0635371418c26b613a6fa68d392f49/softmmu/vl.c#L3352 Should it be "virtio-9p" instead? It's an alias for "virtio-9p-pci", except for s390x, where it's an alias for "virtio-9p-ccw".
On Tue, 31 Mar 2020 18:05:08 +0200 Markus Armbruster <armbru@redhat.com> wrote: > Christian Schoenebeck <qemu_oss@crudebyte.com> writes: > > > On Dienstag, 31. März 2020 17:27:27 CEST Cornelia Huck wrote: > >> > diff --git a/qemu-options.hx b/qemu-options.hx > >> > index 962a5ebaa6..fd3830c6cd 100644 > >> > --- a/qemu-options.hx > >> > +++ b/qemu-options.hx > >> > @@ -1542,9 +1542,17 @@ SRST > >> > > >> > ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag > >> > [,writeout=writeout][,readonly]``> > >> > \ > >> > > >> > ``-virtfs synth,mount_tag=mount_tag`` > >> > > >> > - Define a new filesystem device and expose it to the guest using a > >> > - virtio-9p-device. The general form of a Virtual File system > >> > - pass-through options are: > >> > + Define a new virtual filesystem device and expose it to the guest > >> > using + a virtio-9p-device (a.k.a. 9pfs), which essentially means that > >> > a certain + directory on host is made directly accessible by guest as > >> > a pass-through + file system by using the 9P network protocol for > >> > communication between + host and guests, if desired even accessible, > >> > shared by several guests + simultaniously. > >> > + > >> > + Note that ``-virtfs`` is actually just a convenience shortcut for its > >> > + generalized form ``-fsdev -device virtio-9p-pci``. > >> > >> Huh. This prompted me to try this on s390, and it actually creates a > >> virtio-9p-pci device there as well, not a virtio-9p-ccw device. A bit > >> surprising; but I don't see 9p used much (if at all) on s390 anyway. > > > > Yeah, "virtio-9p-pci" is currently hard coded in softmmu/vl.c [line 3352]: > > https://github.com/qemu/qemu/blob/17083d6d1e0635371418c26b613a6fa68d392f49/softmmu/vl.c#L3352 > > Should it be "virtio-9p" instead? It's an alias for "virtio-9p-pci", > except for s390x, where it's an alias for "virtio-9p-ccw". Seems like a reasonable change (although I'm not sure it matters too much).
On Dienstag, 31. März 2020 18:10:33 CEST Cornelia Huck wrote: > > >> Huh. This prompted me to try this on s390, and it actually creates a > > >> virtio-9p-pci device there as well, not a virtio-9p-ccw device. A bit > > >> surprising; but I don't see 9p used much (if at all) on s390 anyway. > > > > > > Yeah, "virtio-9p-pci" is currently hard coded in softmmu/vl.c [line > > > 3352]: > > > https://github.com/qemu/qemu/blob/17083d6d1e0635371418c26b613a6fa68d392f > > > 49/softmmu/vl.c#L3352> > > Should it be "virtio-9p" instead? It's an alias for "virtio-9p-pci", > > except for s390x, where it's an alias for "virtio-9p-ccw". > > Seems like a reasonable change (although I'm not sure it matters too > much). It would be a minor change it seems, and yes there seems to be a virtio-9p-ccw implementation, however as long as nobody complains I leave it untouched for now. Especially since I have no idea about the s390 architecture, nor testing it. Best regards, Christian Schoenebeck
On Tue, 31 Mar 2020 15:23:38 +0200 Christian Schoenebeck <qemu_oss@crudebyte.com> wrote: > The docs are ambiguous about the difference (or actually their > equality) between options '-virtfs' vs. '-fsdev'. So clarify that > '-virtfs' is actually just a convenience shortcut for its > generalized form '-fsdev' in conjunction with '-device virtio-9p-pci'. > > And as we're at it, also be a bit more descriptive what 9pfs is > actually used for. > > Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com> > --- Applied to 9p-next. > qemu-options.hx | 14 +++++++++++--- > 1 file changed, 11 insertions(+), 3 deletions(-) > > diff --git a/qemu-options.hx b/qemu-options.hx > index 962a5ebaa6..fd3830c6cd 100644 > --- a/qemu-options.hx > +++ b/qemu-options.hx > @@ -1542,9 +1542,17 @@ SRST > ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly]`` > \ > ``-virtfs synth,mount_tag=mount_tag`` > - Define a new filesystem device and expose it to the guest using a > - virtio-9p-device. The general form of a Virtual File system > - pass-through options are: > + Define a new virtual filesystem device and expose it to the guest using > + a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain > + directory on host is made directly accessible by guest as a pass-through > + file system by using the 9P network protocol for communication between > + host and guests, if desired even accessible, shared by several guests > + simultaniously. > + > + Note that ``-virtfs`` is actually just a convenience shortcut for its > + generalized form ``-fsdev -device virtio-9p-pci``. > + > + The general form of pass-through file system options are: > > ``local`` > Accesses to the filesystem are done by QEMU.
diff --git a/qemu-options.hx b/qemu-options.hx index 962a5ebaa6..fd3830c6cd 100644 --- a/qemu-options.hx +++ b/qemu-options.hx @@ -1542,9 +1542,17 @@ SRST ``-virtfs proxy,sock_fd=sock_fd,mount_tag=mount_tag [,writeout=writeout][,readonly]`` \ ``-virtfs synth,mount_tag=mount_tag`` - Define a new filesystem device and expose it to the guest using a - virtio-9p-device. The general form of a Virtual File system - pass-through options are: + Define a new virtual filesystem device and expose it to the guest using + a virtio-9p-device (a.k.a. 9pfs), which essentially means that a certain + directory on host is made directly accessible by guest as a pass-through + file system by using the 9P network protocol for communication between + host and guests, if desired even accessible, shared by several guests + simultaniously. + + Note that ``-virtfs`` is actually just a convenience shortcut for its + generalized form ``-fsdev -device virtio-9p-pci``. + + The general form of pass-through file system options are: ``local`` Accesses to the filesystem are done by QEMU.
The docs are ambiguous about the difference (or actually their equality) between options '-virtfs' vs. '-fsdev'. So clarify that '-virtfs' is actually just a convenience shortcut for its generalized form '-fsdev' in conjunction with '-device virtio-9p-pci'. And as we're at it, also be a bit more descriptive what 9pfs is actually used for. Signed-off-by: Christian Schoenebeck <qemu_oss@crudebyte.com> --- qemu-options.hx | 14 +++++++++++--- 1 file changed, 11 insertions(+), 3 deletions(-)