linux-kernel - Re: [PATCH V2] vhost: do not enable VHOST

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Date:   Fri, 17 Apr 2020 16:51:19 +0800
From:   Jason Wang <jasowang@...hat.com>
To:     "Michael S. Tsirkin" <mst@...hat.com>
Cc:     linux-mips@...r.kernel.org, linux-kernel@...r.kernel.org,
        linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
        kvm@...r.kernel.org, virtualization@...ts.linux-foundation.org,
        netdev@...r.kernel.org, geert@...ux-m68k.org,
        tsbogend@...ha.franken.de, benh@...nel.crashing.org,
        paulus@...ba.org, heiko.carstens@...ibm.com, gor@...ux.ibm.com,
        borntraeger@...ibm.com, Michael Ellerman <mpe@...erman.id.au>
Subject: Re: [PATCH V2] vhost: do not enable VHOST_MENU by default


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<borntraeger@...ibm.com>   (s390)
>>>>>>>> Acked-by: Michael Ellerman<mpe@...erman.id.au>   (powerpc)
>>>>>>>> Cc: Thomas Bogendoerfer<tsbogend@...ha.franken.de>
>>>>>>>> Cc: Benjamin Herrenschmidt<benh@...nel.crashing.org>
>>>>>>>> Cc: Paul Mackerras<paulus@...ba.org>
>>>>>>>> Cc: Michael Ellerman<mpe@...erman.id.au>
>>>>>>>> Cc: Heiko Carstens<heiko.carstens@...ibm.com>
>>>>>>>> Cc: Vasily Gorbik<gor@...ux.ibm.com>
>>>>>>>> Cc: Christian Borntraeger<borntraeger@...ibm.com>
>>>>>>>> Reported-by: Geert Uytterhoeven<geert@...ux-m68k.org>
>>>>>>>> Signed-off-by: Jason Wang<jasowang@...hat.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 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


>