[meta-virtualization] [PATCH V3 2/3] linux-yocto: make bbappend have effect conditionally

[ChenQi]

On 09/27/2017 08:43 PM, Bruce Ashfield wrote:
>
>
> On Tue, Sep 26, 2017 at 4:57 PM, Christopher Clark 
> <christopher.w.clark at gmail.com <mailto:christopher.w.clark at gmail.com>> 
> wrote:
>
>     On Mon, Sep 25, 2017 at 8:31 PM, Chen Qi <Qi.Chen at windriver.com
>     <mailto:Qi.Chen at windriver.com>> wrote:
>     > Make these bbappend files to take effect only when DISTRO_FEATURES
>     > contain 'virtualization'. Otherwise, we would meet failure failure
>     > at system booting up qemux86. Related logs are as below.
>     >
>     >  systemd-modules-load[113]: Failed to insert 'kvm_amd':
>     Operation not supported
>     >  systemd-modules-load[113]: Failed to insert 'kvm_intel':
>     Operation not supported
>     >
>     > Signed-off-by: Chen Qi <Qi.Chen at windriver.com
>     <mailto:Qi.Chen at windriver.com>>
>     ...
>     > diff --git a/recipes-kernel/linux/linux-yocto_virtualization.inc
>     b/recipes-kernel/linux/linux-yocto_virtualization.inc
>     > new file mode 100644
>     > index 0000000..8b296d7
>     > --- /dev/null
>     > +++ b/recipes-kernel/linux/linux-yocto_virtualization.inc
>     > @@ -0,0 +1,20 @@
>     > +FILESEXTRAPATHS_prepend := "${THISDIR}/linux-yocto:"
>     > +
>     > +SRC_URI += "file://xt-checksum.scc \
>     > +            file://ebtables.scc \
>     > +           file://vswitch.scc \
>     > +           file://lxc.scc \
>     > +            file://docker.scc \
>     > +           "
>     > +KERNEL_FEATURES_append = " features/kvm/qemu-kvm-enable.scc"
>     > +
>     > +KERNEL_MODULE_AUTOLOAD += "openvswitch"
>     > +KERNEL_MODULE_AUTOLOAD += "kvm"
>     > +KERNEL_MODULE_AUTOLOAD += "kvm-amd"
>     > +KERNEL_MODULE_AUTOLOAD += "kvm-intel"
>     > +
>     > +# aufs kernel support required for xen-image-minimal
>     > +KERNEL_FEATURES_append +=
>     "${@bb.utils.contains('DISTRO_FEATURES', 'aufs', '
>     features/aufs/aufs-enable.scc', '', d)}"
>     > +
>     > +# xen kernel support
>     > +SRC_URI += "${@bb.utils.contains('DISTRO_FEATURES', 'xen', '
>     file://xen.scc', '', d)}"
>     > --
>     > 2.11.0
>     >
>     > --
>
>     Suggestion for a preferred change: make the KVM features depend on
>     DISTRO_FEATURES containing 'kvm', in the same way that the Xen
>     features do for DISTRO_FEATURES containing 'xen'.
>
>     Here's why: those KVM kernel modules are not of interest on Xen
>     systems. With this change, you're removing the KVM features from the
>     qemu build to solve your bug in hand, by making it conditional on
>     'virtualization', but is still leaves them present when only Xen is
>     needed.
>
>     With that change, I'm not sure whether a 'virtualization' disto
>     feature is immediately useful. It could make sense for features that
>     are hypervisor-agnostic but I don't have an immediate example to point
>     to.
>
>
> I like the suggestion as well. I'd like to future proof this a bit, 
> and we should keep the
> virtualization feature around, but make the KVM features depend on kvm 
> in the
> DISTRO_FEATURES. Less churn on distro flags is a good thing.
>
> Chen Qi, can you rework the check and warning message to reflect that 
> 'kvm'
> is the distro feature to set ?
>
> Bruce
>

Hi Bruce and Christopher,

The status of 'kvm' in yocto (in specific, oe-core layer) is a little 
different from that of 'xen'.

'xen' has been accepted as a distro feature, and the qemu recipe deals 
with it like below.
meta/recipes-devtools/qemu/qemu.inc: 
${@bb.utils.filter('DISTRO_FEATURES', 'alsa xen', d)} \
meta/recipes-devtools/qemu/qemu.inc:PACKAGECONFIG[xen] = 
"--enable-xen,--disable-xen,xen,xen-libxenstore xen-libxenctrl 
xen-libxenguest"

However, for 'kvm', things are different.
It's enabled by default for the qemu (native, nativesdk and target) like 
below.
PACKAGECONFIG ??= " \
         fdt sdl \
         fdt sdl kvm \
         ${@bb.utils.filter('DISTRO_FEATURES', 'alsa xen', d)} \
         "
PACKAGECONFIG_class-native ??= "fdt alsa kvm"
PACKAGECONFIG_class-nativesdk ??= "fdt sdl kvm"
PACKAGECONFIG[kvm] = "--enable-kvm,--disable-kvm"
To make things more complicated, our runqemu script, and the related 
oeqa parts also deal with the 'kvm' parameter.

When talking about 'kvm' above, I'm talking about it from the view of 
treating 'kvm' as a distro feature. I know that enabling kvm for qemu 
and enabling kvm related configs for kernel are two different things, 
although they are somewhat related.

Given the above situation, I'd like to suggest we don't deal with 'kvm' 
in meta-virtualization for now.
I'll find time to see if we can make 'kvm' as a distro feature in 
oe-core. And we deal with 'kvm' in this layer after that.

Best Regards,
Chen Qi

>
>
>     Christopher
>     --
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>
>
>
>
> -- 
> "Thou shalt not follow the NULL pointer, for chaos and madness await 
> thee at its end"


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