Re: [PATCH V2] vhost: do not enable VHOST_MENU by default

["Michael S. Tsirkin" <mst@redhat.com>]

On Fri, Apr 17, 2020 at 04:39:49PM +0800, Jason Wang wrote:
> 
> On 2020/4/17 下午4:29, Michael S. Tsirkin wrote:
> > On Fri, Apr 17, 2020 at 03:36:52PM +0800, Jason Wang wrote:
> > > On 2020/4/17 下午2:33, Michael S. Tsirkin wrote:
> > > > On Fri, Apr 17, 2020 at 11:12:14AM +0800, Jason Wang wrote:
> > > > > On 2020/4/17 上午6:55, Michael S. Tsirkin wrote:
> > > > > > On Wed, Apr 15, 2020 at 10:43:56AM +0800, Jason Wang wrote:
> > > > > > > We try to keep the defconfig untouched after decoupling CONFIG_VHOST
> > > > > > > out of CONFIG_VIRTUALIZATION in commit 20c384f1ea1a
> > > > > > > ("vhost: refine vhost and vringh kconfig") by enabling VHOST_MENU by
> > > > > > > default. Then the defconfigs can keep enabling CONFIG_VHOST_NET
> > > > > > > without the caring of CONFIG_VHOST.
> > > > > > > 
> > > > > > > But this will leave a "CONFIG_VHOST_MENU=y" in all defconfigs and even
> > > > > > > for the ones that doesn't want vhost. So it actually shifts the
> > > > > > > burdens to the maintainers of all other to add "CONFIG_VHOST_MENU is
> > > > > > > not set". So this patch tries to enable CONFIG_VHOST explicitly in
> > > > > > > defconfigs that enables CONFIG_VHOST_NET and CONFIG_VHOST_VSOCK.
> > > > > > > 
> > > > > > > Acked-by: Christian Borntraeger<borntraeger@de.ibm.com>  (s390)
> > > > > > > Acked-by: Michael Ellerman<mpe@ellerman.id.au>  (powerpc)
> > > > > > > Cc: Thomas Bogendoerfer<tsbogend@alpha.franken.de>
> > > > > > > Cc: Benjamin Herrenschmidt<benh@kernel.crashing.org>
> > > > > > > Cc: Paul Mackerras<paulus@samba.org>
> > > > > > > Cc: Michael Ellerman<mpe@ellerman.id.au>
> > > > > > > Cc: Heiko Carstens<heiko.carstens@de.ibm.com>
> > > > > > > Cc: Vasily Gorbik<gor@linux.ibm.com>
> > > > > > > Cc: Christian Borntraeger<borntraeger@de.ibm.com>
> > > > > > > Reported-by: Geert Uytterhoeven<geert@linux-m68k.org>
> > > > > > > Signed-off-by: Jason Wang<jasowang@redhat.com>
> > > > > > I rebased this on top of OABI fix since that
> > > > > > seems more orgent to fix.
> > > > > > Pushed to my vhost branch pls take a look and
> > > > > > if possible test.
> > > > > > Thanks!
> > > > > I test this patch by generating the defconfigs that wants vhost_net or
> > > > > vhost_vsock. All looks fine.
> > > > > 
> > > > > But having CONFIG_VHOST_DPN=y may end up with the similar situation that
> > > > > this patch want to address.
> > > > > Maybe we can let CONFIG_VHOST depends on !ARM || AEABI then add another
> > > > > menuconfig for VHOST_RING and do something similar?
> > > > > 
> > > > > Thanks
> > > > Sorry I don't understand. After this patch CONFIG_VHOST_DPN is just
> > > > an internal variable for the OABI fix. I kept it separate
> > > > so it's easy to revert for 5.8. Yes we could squash it into
> > > > VHOST directly but I don't see how that changes logic at all.
> > > 
> > > Sorry for being unclear.
> > > 
> > > I meant since it was enabled by default, "CONFIG_VHOST_DPN=y" will be left
> > > in the defconfigs.
> > But who cares?
> 
> 
> FYI, please see https://www.spinics.net/lists/kvm/msg212685.html

The complaint was not about the symbol IIUC.  It was that we caused
everyone to build vhost unless they manually disabled it.

> 
> > That does not add any code, does it?
> 
> 
> It doesn't.
> 
> Thanks
> 
> 
> > 
> > > This requires the arch maintainers to add
> > > "CONFIG_VHOST_VDPN is not set". (Geert complains about this)
> > > 
> > > Thanks
> > > 
> > >