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Re: [PATCH v4 10/11] 9p: darwin: meson: Allow VirtFS on Darwin
From: |
Greg Kurz |
Subject: |
Re: [PATCH v4 10/11] 9p: darwin: meson: Allow VirtFS on Darwin |
Date: |
Mon, 7 Feb 2022 15:39:30 +0100 |
On Mon, 07 Feb 2022 15:15:46 +0100
Christian Schoenebeck <qemu_oss@crudebyte.com> wrote:
> On Montag, 7. Februar 2022 02:05:32 CET Will Cohen wrote:
> > On Sun, Feb 6, 2022 at 4:22 PM Philippe Mathieu-Daudé <f4bug@amsat.org>
> >
> > wrote:
> > > On 6/2/22 21:07, Will Cohen wrote:
> > > > From: Keno Fischer <keno@juliacomputing.com>
> > > >
> > > > Signed-off-by: Keno Fischer <keno@juliacomputing.com>
> > > > [Michael Roitzsch: - Rebase for NixOS]
> > > > Signed-off-by: Michael Roitzsch <reactorcontrol@icloud.com>
> > > > [Will Cohen: - Rebase to master]
> > > > Signed-off-by: Will Cohen <wwcohen@gmail.com>
> > > > Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
> > > > [Will Cohen: - Add check for pthread_fchdir_np to virtfs]
> > > > Signed-off-by: Will Cohen <wwcohen@gmail.com>
> > > > ---
> > > >
> > > > fsdev/meson.build | 1 +
> > > > meson.build | 14 ++++++++++----
> > > > 2 files changed, 11 insertions(+), 4 deletions(-)
> > > >
> > > > -have_virtfs_proxy_helper = have_virtfs and have_tools
> > > > +have_virtfs_proxy_helper = targetos == 'linux' and have_virtfs and
> > >
> > > have_tools
> > >
> > > Why do you restrict the proxy-helper to Linux?
> >
> > Only because porting the proxy-helper to macOS is outside the scope of this
> > particular patch. While some initial concepts around it have been
> > considered by some of the contributors to this patch, those implementations
> > weren't tested enough and the security implications weren't considered in
> > full. We assume that this could be an additional implementation later on,
> > if the functionality is considered important down the road.
>
> In general that's fine with me. I would have probably made that
> "targetos != 'darwin'" instead of "targetos == 'linux'", but I leave that up
> to you.
>
> On the long term we will probably deprecate the 9p 'proxy' fs driver anyway.
> While it had some good ideas, being realistic though: nobody has worked on
> the
> 9p proxy driver/backend for many years and it is not in good shape.
>
It definitely isn't indeed. Also it is super slow by design
since the round trip of a 9p request involves QEMU on both entry
and exit:
[guest] --> [QEMU]--> [virtfs-proxy-helper]-->[QEMU]-->[guest]
A more modern and efficient approach would be to have a vhost-user-9p
implementation : requests would be directly handled by the external
process, without QEMU hops. But this a fair amount of work.
> I can imagine that due to the ground being laid by these series, that we will
> also open 9p for BSD, but that should be done a bit later and hence does not
> belong into these series.
>
> But once again: it would not have hurt to make your intentions clear either
> in
> the commit log or by in-source comment. :)
>
> Best regards,
> Christian Schoenebeck
>
>
[PATCH v4 05/11] 9p: darwin: Ignore O_{NOATIME, DIRECT}, Will Cohen, 2022/02/06
[PATCH v4 07/11] 9p: darwin: *xattr_nofollow implementations, Will Cohen, 2022/02/06
[PATCH v4 10/11] 9p: darwin: meson: Allow VirtFS on Darwin, Will Cohen, 2022/02/06
Re: [PATCH v4 10/11] 9p: darwin: meson: Allow VirtFS on Darwin, Christian Schoenebeck, 2022/02/07
[PATCH v4 11/11] 9p: darwin: Adjust assumption on virtio-9p-test, Will Cohen, 2022/02/06
Re: [PATCH v4 00/11] 9p: Add support for darwin, Christian Schoenebeck, 2022/02/07