On Fri, Jan 6, 2023 at 6:27 AM Richard Purdie
<[email protected]> wrote:
>
> On Fri, 2023-01-06 at 11:13 +0100, Mark Jonas wrote:
> > Hi Bruce,
> >
> > On Thu, Jan 5, 2023 at 3:57 PM Bruce Ashfield <[email protected]>
> > wrote:
> > >
> > > On Thu, Jan 5, 2023 at 8:42 AM Mark Jonas <[email protected]> wrote:
> > > >
> > > > Hi Bruce,
> > > >
> > > > On Wed, Jan 4, 2023 at 5:07 PM Bruce Ashfield
> > > > <[email protected]> wrote:
> > > > >
> > > > > On Wed, Jan 4, 2023 at 7:18 AM Mark Jonas <[email protected]> wrote:
> > > > > >
> > > > > > From: Mark Jonas <[email protected]>
> > > > > >
> > > > > > If DISTRO_FEATURES includes ALSA then automatically load the
> > > > > > snd-intel8x0 kernel module on qemux86 and qemux86-64. This matches
> > > > > > the
> > > > > > machine configurations conf/machine/qemux86.conf and
> > > > > > qemux86-64.conf.
> > > > > >
> > > > > > Signed-off-by: Mark Jonas <[email protected]>
> > > > > > ---
> > > > > > meta/recipes-kernel/linux/linux-yocto.inc | 5 +++++
> > > > > > 1 file changed, 5 insertions(+)
> > > > > >
> > > > > > diff --git a/meta/recipes-kernel/linux/linux-yocto.inc
> > > > > > b/meta/recipes-kernel/linux/linux-yocto.inc
> > > > > > index 091003ed82..c8a9b0a1e3 100644
> > > > > > --- a/meta/recipes-kernel/linux/linux-yocto.inc
> > > > > > +++ b/meta/recipes-kernel/linux/linux-yocto.inc
> > > > > > @@ -37,6 +37,11 @@ KERNEL_FEATURES:append = "
> > > > > > ${@bb.utils.contains('MACHINE_FEATURES', 'efi', 'cfg/
> > > > > > KERNEL_FEATURES:append = "
> > > > > > ${@bb.utils.contains('MACHINE_FEATURES', 'numa',
> > > > > > 'features/numa/numa.scc', '', d)}"
> > > > > > KERNEL_FEATURES:append = "
> > > > > > ${@bb.utils.contains('MACHINE_FEATURES', 'vfat', 'cfg/fs/vfat.scc',
> > > > > > '', d)}"
> > > > > >
> > > > > > +# sound driver recommended by conf/machine/qemux86*.conf
> > > > > > +ALSA_MODULES = "${@bb.utils.contains("DISTRO_FEATURES", "alsa",
> > > > > > "snd-intel8x0", "", d)}"
> > > > > > +KERNEL_MODULE_AUTOLOAD:qemux86 += "${ALSA_MODULES}"
> > > > > > +KERNEL_MODULE_AUTOLOAD:qemux86-64 += "${ALSA_MODULES}"
> > > > >
> > > > > This gets us most of the way, but if we are going to do this we should
> > > > > complete the job.
> > > > >
> > > > > We really need to make sure there's a configuration fragment that
> > > > > explicitly enables
> > > > > the modules we need (and not count on defaults, or other selects).
> > > > > That would go
> > > > > into the kernel-cache.
> > > > >
> > > > > It would then be something we'd add to the KERNEL_FEATRES triggered
> > > > > off the
> > > > > distro feature. Just like we are doing with numa and vfat that is
> > > > > visible in the
> > > > > context of the patch.
> > > >
> > > > In my understanding this is already the case. See for example
> > > > linux-yocto_5.19.bb which contains the following lines.
> > > >
> > > > KERNEL_FEATURES:append:qemux86=" cfg/sound.scc cfg/paravirt_kvm.scc"
> > > > KERNEL_FEATURES:append:qemux86-64=" cfg/sound.scc cfg/paravirt_kvm.scc"
> > > >
> > > > Does that maybe mean I should better add the KERNEL_MODULE_AUTOLOAD
> > > > into the same file where the corresponding configuration fragment is
> > > > added? But that would mean to duplicate the lines over five recipes.
> > > >
> > > > Alternatively I could move the cfg/sound.scc out of the recipes into
> > > > the linux-yocto.inc. But then linux-yocto-tiny_*.bb recipes would also
> > > > get it.
> > >
> > > I definitely wasn't clear. Sorry about that, I'm still partially on
> > > holidays and didn't have enough coffee when I wrote that.
> > >
> > > That is close to what I meant. It is one thing to define the options
> > > in our generic sound "buckets" and another to put a specific module
> > > into the autoload.
> > >
> > > If we are going to autoload a module, the option really should be
> > > pulled out of the generic bucket, and put into something smaller /
> > > specific to what we are trying to do, and trigger the inclusion of
> > > that fragment only when the appropriate distro feature is set. The
> > > machine conf files specifying specific modules isn't ideal, since it
> > > is largely "aspirational" unless it is coupled with a KERNEL_FEATURE
> > > that is set based on a machine or distro feature.
> >
> > I have to admit that I feel a bit lost. I am not really sure I
> > understood what you meant.
> >
> > Is the "generic bucket" cfg/sound.scc? But why should we break that
> > up? A module only ends up in an image if the module is installed. And
> > the installation is controlled e.g. by MACHINE_EXTRA_RRECOMMENDS in
> > the machine file.
>
> I might also be misunderstanding but I think what Bruce is asking is
> that the qemux86 sound pieces be broken out of cfg/sound.scc. In case
> you didn't find them, the files are here:
>
> https://git.yoctoproject.org/yocto-kernel-cache/tree/cfg/sound.scc
> https://git.yoctoproject.org/yocto-kernel-cache/tree/cfg/sound.cfg
>
> and the question is which of the options in sound.cfg are the drivers
> which qemu needs on x86.
>
> I think Bruce would like a patch which splits those items out and
> triggers them on qemux86 specifically.
>
> This means if things change in future, we know exactly which module
> options we need for sound on qemux86.
>
> Bruce can correct me if I misunderstand! :)
That is correct!
Something like sonud-intel.scc/cfg or sound-qemu.scc/cfg that just contains
what we need for those particular drivers, as they have a well defined
use case, and there's no need for ALL the other drivers to be enabled,
built and packaged if you really know your target machine.
The KERNEL_FEATURES append would then be something like:
SOUND_FEATURES="${@bb.utils.contains('MACHINE_FEATURES', 'alsa',
'cfg/sound-intel.scc', '', d)}"
KERNEL_FEATURES:append:qemux86=" ${SOUND_FEATURES} cfg/paravirt_kvm.scc"
Or it could all be done in the single append, etc, but having it in a
variable might
give us more flexibility for other qemu or target machines to re-use it.
My example keeps the machine specific enablement in the KERNEL_FEATURES
append, but there are any number of ways to do it (since my proposed
configuration
fragment has "intel" in it, it could be confusing :))
Bruce
>
> > > If you search the mailing list archives, you'll see me musing about
> > > how I need to change those unconditional appends of option to qemu, as
> > > it makes defining a new qemu machine problematic (if the options are
> > > causing issues). The tweak I'm describing is a small step in that
> > > direction.
> >
> > What I understood is that you propose to change the existing
> >
> > KERNEL_FEATURES:append:qemux86=" cfg/sound.scc cfg/paravirt_kvm.scc"
> > KERNEL_FEATURES:append:qemux86-64=" cfg/sound.scc cfg/paravirt_kvm.scc"
> >
> > in e.g. linux-yocto_5.19.bb to (remove cfg/sound.scc)
> >
> > KERNEL_FEATURES:append:qemux86=" cfg/paravirt_kvm.scc"
> > KERNEL_FEATURES:append:qemux86-64=" cfg/paravirt_kvm.scc"
> >
> > and add (move) the following into linux-yocto.inc
> >
> > KERNEL_FEATURES:append:qemuall="
> > ${@bb.utils.contains('MACHINE_FEATURES', 'alsa', 'cfg/sound.scc', '',
> > d)}"
> >
> > That is, instead of coupling the compilation of QEMU sound driver
> > modules based on machine name qemux86 and qemux86-64 we activate it
> > for all QEMU machines which also have alsa as a MACHINE_FEATURE. And
> > that is set in machine/include/qemu.inc.
> >
> > > One new question comes to mind, what init system were you testing with
> > > (default poky and sysvinit ?) ? If we now have the proper init system,
> > > are no events being triggered to load the modules now that the proper
> > > ones are in the machine files ?
> >
> > I was testing on Poky with the default init system i.e, sysvinit.
> > Without the KERNEL_MODULE_AUTOLOAD line the snd-intel8x0 module is not
> > loaded.
> >
> > And it seems you are right: The KERNEL_MODULE_AUTOLOAD is superfluous.
> > Even when I remove the second patch the modules are still loaded. I am
> > a little puzzled why it originally seemed to me that it was necessary.
>
> I'm not sure on that. The kernel will try and autoprobe for drivers for
> hardware it has present where it can though.
>
> Cheers,
>
> Richard
>
>
--
- Thou shalt not follow the NULL pointer, for chaos and madness await
thee at its end
- "Use the force Harry" - Gandalf, Star Trek II
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