> -----Original Message----- > From: George Dunlap [mailto:[email protected]] > Sent: 06 September 2018 13:52 > To: Paul Durrant <[email protected]>; [email protected] > Cc: Andrew Cooper <[email protected]>; George Dunlap > <[email protected]>; Ian Jackson <[email protected]>; Jan > Beulich <[email protected]>; Julien Grall <[email protected]>; Konrad > Rzeszutek Wilk <[email protected]>; Stefano Stabellini > <[email protected]>; Tim (Xen.org) <[email protected]>; Wei Liu > <[email protected]> > Subject: Re: [PATCH] tools: specifically enable VirtFS in Linux QEMU builds > > On 09/06/2018 01:06 PM, Paul Durrant wrote: > > 9pfs support has been a documented feature since Xen 4.9, but QEMU will > > not be built with backend support unless libcap and libattr dev packages > > are installed. > > > > This patch modifies the README to call out those packages as pre- > requisites > > for Linux builds and specifically enables VirtFS in the configure line > > for QEMU so that an error message is displayed if they are missing. > > > > Signed-off-by: Paul Durrant <[email protected]> > > --- > > Cc: Andrew Cooper <[email protected]> > > Cc: George Dunlap <[email protected]> > > Cc: Ian Jackson <[email protected]> > > Cc: Jan Beulich <[email protected]> > > Cc: Julien Grall <[email protected]> > > Cc: Konrad Rzeszutek Wilk <[email protected]> > > Cc: Stefano Stabellini <[email protected]> > > Cc: Tim Deegan <[email protected]> > > Cc: Wei Liu <[email protected]> > > --- > > README | 2 ++ > > tools/Makefile | 11 +++++++++++ > > 2 files changed, 13 insertions(+) > > > > diff --git a/README b/README > > index 4b95b21c7b..1a4e4b2c1b 100644 > > --- a/README > > +++ b/README > > @@ -56,6 +56,8 @@ provided by your OS distributor: > > greater. > > * Development install of GLib v2.0 (e.g. libglib2.0-dev) > > * Development install of Pixman (e.g. libpixman-1-dev) > > + * Development install of libcap (e.g. libcap-dev) [Linux only] > > + * Development install of libattr (e.g. libattr1-dev) [Linux only] > > * pkg-config > > * bridge-utils package (/sbin/brctl) > > * iproute package (/sbin/ip) > > diff --git a/tools/Makefile b/tools/Makefile > > index 67977ad850..e74efb8a6e 100644 > > --- a/tools/Makefile > > +++ b/tools/Makefile > > @@ -216,6 +216,11 @@ else > > QEMU_XEN_ENABLE_DEBUG := > > endif > > > > +# > > +# 9pfs support is a documented feature but it depends on a QEMU with > > +# VirtFS enabled. However VirtFS is a Linux-only option so only enable > > +# it for Linux builds. > > +# > > subdir-all-qemu-xen-dir: qemu-xen-dir-find > > unset MAKELEVEL; \ > > if test -d $(QEMU_UPSTREAM_LOC) ; then \ > > @@ -232,10 +237,16 @@ subdir-all-qemu-xen-dir: qemu-xen-dir-find > > else \ > > enable_trace_backend='' ; \ > > fi ; \ > > + if [ "$(CONFIG_Linux)" = "y" ]; then \ > > + enable_virtfs='--enable-virtfs' ; \ > > + else \ > > + enable_virtfs='' ; \ > > + fi ; \ > > 9pfs is still a reasonably "niche" feature; I don't think we want to > force people to enable it if they don't expect to use it. > > Is it the case that if we have libcap and libattr, that qemu will enable > 9pfs automatically? If so we should just document that.
Yes, that is the case but it does seem weird that we have a documented feature which is not being built in by default, because we don't call out or check for the necessary pre-requisites. > > Another option would be to have "--enable-9pfs" option in the tools > configure, which would then pass this on to qemu (and thus fail if the > requisite librares aren't present), but I'm not sure if having a load of > "--enable-*" at the top level is really what we want for this. > That is something I wondered about. Really I just don't want people to be scrobbling around wondering why, having built and installed Xen and QEMU put a '9p' line in their config and then kicked off their guest, it simply doesn't work. Paul > -George _______________________________________________ Xen-devel mailing list [email protected] https://lists.xenproject.org/mailman/listinfo/xen-devel
