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Re: [Qemu-devel] [PATCH v2 1/9] configure: change CONFIG_XEN_BACKEND to
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [PATCH v2 1/9] configure: change CONFIG_XEN_BACKEND to be a target property |
Date: |
Tue, 14 Mar 2017 12:07:55 -0700 (PDT) |
User-agent: |
Alpine 2.10 (DEB 1266 2009-07-14) |
On Tue, 14 Mar 2017, Paolo Bonzini wrote:
> On 14/03/2017 00:55, Stefano Stabellini wrote:
> > CONFIG_XEN_BACKEND is currently set when the host supports Xen,
> > regardless of the chosen targets. As a consequence, Xen backends can be
> > enabled even on targets that don't support Xen.
> >
> > Fix the issue by setting CONFIG_XEN_BACKEND only for targets that
> > support Xen.
> >
> > Signed-off-by: Stefano Stabellini <address@hidden>
> > CC: address@hidden
> > CC: address@hidden
> > CC: address@hidden
> > CC: address@hidden
> > CC: address@hidden
> > CC: address@hidden
> > ---
> > configure | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/configure b/configure
> > index 6c21975..6d8f752 100755
> > --- a/configure
> > +++ b/configure
> > @@ -5442,7 +5442,6 @@ if test "$virglrenderer" = "yes" ; then
> > echo "VIRGL_LIBS=$virgl_libs" >> $config_host_mak
> > fi
> > if test "$xen" = "yes" ; then
> > - echo "CONFIG_XEN_BACKEND=y" >> $config_host_mak
> > echo "CONFIG_XEN_CTRL_INTERFACE_VERSION=$xen_ctrl_version" >>
> > $config_host_mak
> > if test "$xen_pv_domain_build" = "yes" ; then
> > echo "CONFIG_XEN_PV_DOMAIN_BUILD=y" >> $config_host_mak
> > @@ -6028,6 +6027,7 @@ case "$target_name" in
> > i386|x86_64)
> > if test "$xen" = "yes" -a "$target_softmmu" = "yes" ; then
> > echo "CONFIG_XEN=y" >> $config_target_mak
> > + echo "CONFIG_XEN_BACKEND=y" >> $config_target_mak
> > if test "$xen_pci_passthrough" = yes; then
> > echo "CONFIG_XEN_PCI_PASSTHROUGH=y" >> "$config_target_mak"
> > fi
> >
>
> This messes up a bit the way xen_nic.o and friends are compiled, I
> think, because they are common-obj-y but they are only found when
> compiling in the target subdirectories. So you end up building
> x86_64-softmmu/../hw/net/xen_nic.o
>
> If you're unlucky, I believe this can lead to a link failure where a
> target is building xen_nic.o, while the other tries to link to a
> partially written object file.
>
> I think the files should be changed from
> common-obj-$(CONFIG_XEN_BACKEND) to common-obj-$(CONFIG_XEN).
>
> The Makefile.objs change ensures that Xen backends are not enabled on
> targets that support Xen.
Actually I thought about doing that instead of the configure change. It
makes sense to me.
> Then you add to Makefile:
>
> CONFIG_SOFTMMU := $(if $(filter %-softmmu,$(TARGET_DIRS)),y)
> CONFIG_USER_ONLY := $(if $(filter %-user,$(TARGET_DIRS)),y)
> +CONFIG_XEN := $(CONFIG_XEN_BACKEND)
> CONFIG_ALL=y
> -include config-all-devices.mak
> -include config-all-disas.mak
>
> The Makefile change ensures that they are built before descending in the
> target-specific directories.
But I don't understand this. Please correct me if I am wrong, but this
change looks like it would end up setting CONFIG_XEN every time that
CONFIG_XEN_BACKEND is set. Without the configure change at the top, it
would end up setting CONFIG_XEN whenever the host supports Xen, even for
non-x86 and non-ARM targets. What am I missing?
- [Qemu-devel] [PATCH v2 9/9] xen/9pfs: build and register Xen 9pfs backend, (continued)
[Qemu-devel] [PATCH v2 8/9] xen/9pfs: send responses back to the frontend, Stefano Stabellini, 2017/03/13
Re: [Qemu-devel] [PATCH v2 1/9] configure: change CONFIG_XEN_BACKEND to be a target property, Paolo Bonzini, 2017/03/14