Re: [PATCH V9 1/9] vhost: refine vhost and vringh kconfig
From: Jason Wang
Date: Wed Apr 01 2020 - 10:51:21 EST
On 2020/4/1 äå10:27, Michael S. Tsirkin wrote:
On Wed, Apr 01, 2020 at 10:13:29PM +0800, Jason Wang wrote:
On 2020/4/1 äå9:02, Christian Borntraeger wrote:
On 01.04.20 14:56, Christian Borntraeger wrote:
On 01.04.20 14:50, Jason Wang wrote:
On 2020/4/1 äå7:21, Christian Borntraeger wrote:
On 26.03.20 15:01, Jason Wang wrote:
Currently, CONFIG_VHOST depends on CONFIG_VIRTUALIZATION. But vhost is
not necessarily for VM since it's a generic userspace and kernel
communication protocol. Such dependency may prevent archs without
virtualization support from using vhost.
To solve this, a dedicated vhost menu is created under drivers so
CONIFG_VHOST can be decoupled out of CONFIG_VIRTUALIZATION.
FWIW, this now results in vhost not being build with defconfig kernels (in todays
linux-next).
Hi Christian:
Did you meet it even with this commitÂhttps://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=a4be40cbcedba9b5b714f3c95182e8a45176e42d?
I simply used linux-next. The defconfig does NOT contain CONFIG_VHOST and therefore CONFIG_VHOST_NET and friends
can not be selected.
$ git checkout next-20200401
$ make defconfig
HOSTCC scripts/basic/fixdep
HOSTCC scripts/kconfig/conf.o
HOSTCC scripts/kconfig/confdata.o
HOSTCC scripts/kconfig/expr.o
LEX scripts/kconfig/lexer.lex.c
YACC scripts/kconfig/parser.tab.[ch]
HOSTCC scripts/kconfig/lexer.lex.o
HOSTCC scripts/kconfig/parser.tab.o
HOSTCC scripts/kconfig/preprocess.o
HOSTCC scripts/kconfig/symbol.o
HOSTCC scripts/kconfig/util.o
HOSTLD scripts/kconfig/conf
*** Default configuration is based on 'x86_64_defconfig'
#
# configuration written to .config
#
$ grep VHOST .config
# CONFIG_VHOST is not set
If yes, what's your build config looks like?
Thanks
This was x86. Not sure if that did work before.
On s390 this is definitely a regression as the defconfig files
for s390 do select VHOST_NET
grep VHOST arch/s390/configs/*
arch/s390/configs/debug_defconfig:CONFIG_VHOST_NET=m
arch/s390/configs/debug_defconfig:CONFIG_VHOST_VSOCK=m
arch/s390/configs/defconfig:CONFIG_VHOST_NET=m
arch/s390/configs/defconfig:CONFIG_VHOST_VSOCK=m
and this worked with 5.6, but does not work with next. Just adding
CONFIG_VHOST=m to the defconfig solves the issue, something like
Right, I think we probably need
1) add CONFIG_VHOST=m to all defconfigs that enables
CONFIG_VHOST_NET/VSOCK/SCSI.
or
2) don't use menuconfig for CONFIG_VHOST, let NET/SCSI/VDPA just select it.
Thanks
OK I tried this:
diff --git a/drivers/vhost/Kconfig b/drivers/vhost/Kconfig
index 2523a1d4290a..a314b900d479 100644
--- a/drivers/vhost/Kconfig
+++ b/drivers/vhost/Kconfig
@@ -19,11 +19,10 @@ menuconfig VHOST
This option is selected by any driver which needs to access
the core of vhost.
-if VHOST
-
config VHOST_NET
tristate "Host kernel accelerator for virtio net"
depends on NET && EVENTFD && (TUN || !TUN) && (TAP || !TAP)
+ select VHOST
---help---
This kernel module can be loaded in host kernel to accelerate
guest networking with virtio_net. Not to be confused with virtio_net
@@ -35,6 +34,7 @@ config VHOST_NET
config VHOST_SCSI
tristate "VHOST_SCSI TCM fabric driver"
depends on TARGET_CORE && EVENTFD
+ select VHOST
default n
---help---
Say M here to enable the vhost_scsi TCM fabric module
@@ -44,6 +44,7 @@ config VHOST_VSOCK
tristate "vhost virtio-vsock driver"
depends on VSOCKETS && EVENTFD
select VIRTIO_VSOCKETS_COMMON
+ select VHOST
default n
---help---
This kernel module can be loaded in the host kernel to provide AF_VSOCK
@@ -57,6 +58,7 @@ config VHOST_VDPA
tristate "Vhost driver for vDPA-based backend"
depends on EVENTFD
select VDPA
+ select VHOST
help
This kernel module can be loaded in host kernel to accelerate
guest virtio devices with the vDPA-based backends.
@@ -78,5 +80,3 @@ config VHOST_CROSS_ENDIAN_LEGACY
adds some overhead, it is disabled by default.
If unsure, say "N".
-
-endif
But now CONFIG_VHOST is always "y", never "m".
Which I think will make it a built-in.
Didn't figure out why yet.
Is it because the dependency of EVENTFD for CONFIG_VHOST?
Remove that one for this patch, I can get CONFIG_VHOST=m.
But according to documentation/kbuild/kconfig.rst, select is used for
option without prompt.
Thanks