From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH V2] vhost: do not enable VHOST_MENU by default Date: Fri, 17 Apr 2020 04:57:41 -0400 Message-ID: <20200417045454-mutt-send-email-mst@kernel.org> References: <20200415024356.23751-1-jasowang@redhat.com> <20200416185426-mutt-send-email-mst@kernel.org> <20200417022929-mutt-send-email-mst@kernel.org> <4274625d-6feb-81b6-5b0a-695229e7c33d@redhat.com> <20200417042912-mutt-send-email-mst@kernel.org> <20200417044230-mutt-send-email-mst@kernel.org> <73843240-3040-655d-baa9-683341ed4786@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Return-path: Content-Disposition: inline In-Reply-To: <73843240-3040-655d-baa9-683341ed4786@redhat.com> Sender: linux-kernel-owner@vger.kernel.org To: Jason Wang Cc: linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, geert@linux-m68k.org, tsbogend@alpha.franken.de, benh@kernel.crashing.org, paulus@samba.org, heiko.carstens@de.ibm.com, gor@linux.ibm.com, borntraeger@de.ibm.com, Michael Ellerman List-Id: virtualization@lists.linuxfoundation.org On Fri, Apr 17, 2020 at 04:51:19PM +0800, Jason Wang wrote: > > On 2020/4/17 下午4:46, Michael S. Tsirkin wrote: > > 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 (s390) > > > > > > > > > Acked-by: Michael Ellerman (powerpc) > > > > > > > > > Cc: Thomas Bogendoerfer > > > > > > > > > Cc: Benjamin Herrenschmidt > > > > > > > > > Cc: Paul Mackerras > > > > > > > > > Cc: Michael Ellerman > > > > > > > > > Cc: Heiko Carstens > > > > > > > > > Cc: Vasily Gorbik > > > > > > > > > Cc: Christian Borntraeger > > > > > > > > > Reported-by: Geert Uytterhoeven > > > > > > > > > Signed-off-by: Jason Wang > > > > > > > > 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 seehttps://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. > > > There could be some misunderstanding here. I thought it's somehow similar: a > CONFIG_VHOST_MENU=y will be left in the defconfigs even if CONFIG_VHOST is > not set. > > Thanks Hmm. So looking at Documentation/kbuild/kconfig-language.rst : Things that merit "default y/m" include: a) A new Kconfig option for something that used to always be built should be "default y". b) A new gatekeeping Kconfig option that hides/shows other Kconfig options (but does not generate any code of its own), should be "default y" so people will see those other options. c) Sub-driver behavior or similar options for a driver that is "default n". This allows you to provide sane defaults. So it looks like VHOST_MENU is actually matching rule b). So what's the problem we are trying to solve with this patch, exactly? Geert could you clarify pls? > > >