Re: [Xen-devel] [PATCH 1/4] xen kconfig: keep XEN_XENBUS_FRONTEND builtin

Re: [Xen-devel] [PATCH 1/4] xen kconfig: keep XEN_XENBUS_FRONTEND builtin

[Andrew Jones]

----- Original Message -----
> On Wed, Jan 11, 2012 at 05:36:38PM +0100, Andrew Jones wrote:
> > When XEN_XENBUS_FRONTEND gets selected as a module it can lead to
> > unbootable configs. If we need it, then we should just build it in.
> 
> Hm, don't the frontends by themsevles load this module? So if you
> do 'modprobe xen-pcifront' it would load this automatically?
> 

The problem is on boot, getting it there before we need xen-blkfront.
I think it might solvable if you make sure your tooling pushes the
xenbus module into your initrd. However we've had problems with
platform_pci being a module in the past, and if I'm not mistaken
that was one of the motivators for building it in (5fbdc10395cd). I
see this as a similar story.

Drew

> > 
> > Signed-off-by: Andrew Jones <drjones@redhat.com>
> > ---
> >  drivers/xen/Kconfig |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> > index 8795480..1d24061 100644
> > --- a/drivers/xen/Kconfig
> > +++ b/drivers/xen/Kconfig
> > @@ -118,7 +118,7 @@ config XEN_SYS_HYPERVISOR
> >  	 but will have no xen contents.
> >  
> >  config XEN_XENBUS_FRONTEND
> > -	tristate
> > +	bool
> >  
> >  config XEN_GNTDEV
> >  	tristate "userspace grant access device driver"
> > --
> > 1.7.7.5
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
> 

Re: [Xen-devel] [PATCH 1/4] xen kconfig: keep XEN_XENBUS_FRONTEND builtin

[Konrad Rzeszutek Wilk]

On Thu, Jan 12, 2012 at 05:49:57AM -0500, Andrew Jones wrote:
> 
> 
> ----- Original Message -----
> > On Wed, Jan 11, 2012 at 05:36:38PM +0100, Andrew Jones wrote:
> > > When XEN_XENBUS_FRONTEND gets selected as a module it can lead to
> > > unbootable configs. If we need it, then we should just build it in.
> > 
> > Hm, don't the frontends by themsevles load this module? So if you
> > do 'modprobe xen-pcifront' it would load this automatically?
> > 
> 
> The problem is on boot, getting it there before we need xen-blkfront.
> I think it might solvable if you make sure your tooling pushes the
> xenbus module into your initrd. However we've had problems with

So it seems we also need patches for dracut and initramfs here?

Or is it possible to make the modules (fb) try to load xenbus frontend
automatically? Preferrably one would do this:

modprobe xen_fbfront
which would then automatically load xenbus_module, xen_kbdfront

Better yet if udev/kudzu figured out this automtically and loaded
the modules.

Is there a mechanism to automatically have udev do all of this loading?
Let CC the Debian maintainer on this converstation as he might have
some ideas in this.


> platform_pci being a module in the past, and if I'm not mistaken

Right, but that driver is not tied in with the frontends. It just
pokes at the ioport to disable QEMU HVM drivers.

> that was one of the motivators for building it in (5fbdc10395cd). I
> see this as a similar story.
> 
> Drew
> 
> > > 
> > > Signed-off-by: Andrew Jones <drjones@redhat.com>
> > > ---
> > >  drivers/xen/Kconfig |    2 +-
> > >  1 files changed, 1 insertions(+), 1 deletions(-)
> > > 
> > > diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> > > index 8795480..1d24061 100644
> > > --- a/drivers/xen/Kconfig
> > > +++ b/drivers/xen/Kconfig
> > > @@ -118,7 +118,7 @@ config XEN_SYS_HYPERVISOR
> > >  	 but will have no xen contents.
> > >  
> > >  config XEN_XENBUS_FRONTEND
> > > -	tristate
> > > +	bool
> > >  
> > >  config XEN_GNTDEV
> > >  	tristate "userspace grant access device driver"
> > > --
> > > 1.7.7.5
> > 
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel
> > 

Re: [Xen-devel] [PATCH 1/4] xen kconfig: keep XEN_XENBUS_FRONTEND builtin

[Bastian Blank]

On Thu, Jan 12, 2012 at 09:37:45AM -0500, Konrad Rzeszutek Wilk wrote:
> Or is it possible to make the modules (fb) try to load xenbus frontend
> automatically? Preferrably one would do this:

Which modules?

> modprobe xen_fbfront
> which would then automatically load xenbus_module, xen_kbdfront

I think you are missing something.

| video/xen-fbfront.c:      return xenbus_register_frontend(&xenfb_driver);
| xen/xenbus/xenbus_probe_frontend.c:EXPORT_SYMBOL_GPL(xenbus_register_frontend);

xen-fbfront already pulls in the module, at least in Linus' tree.

> Better yet if udev/kudzu figured out this automtically and loaded
> the modules.

No workarounds for kernel problems if not absolutely necessary.

Bastian

-- 
Military secrets are the most fleeting of all.
		-- Spock, "The Enterprise Incident", stardate 5027.4

Re: [Xen-devel] [PATCH 1/4] xen kconfig: keep XEN_XENBUS_FRONTEND builtin

[Andrew Jones]

----- Original Message -----
> On Thu, Jan 12, 2012 at 09:37:45AM -0500, Konrad Rzeszutek Wilk
> wrote:
> > Or is it possible to make the modules (fb) try to load xenbus
> > frontend
> > automatically? Preferrably one would do this:
> 
> Which modules?
> 
> > modprobe xen_fbfront
> > which would then automatically load xenbus_module, xen_kbdfront
> 
> I think you are missing something.

I'll look into this and see if I can get the xenbus module to
work on boot with the right initrd magic. Or at least come up with
a better story why it won't.

Drew

> 
> | video/xen-fbfront.c:      return
> | xenbus_register_frontend(&xenfb_driver);
> | xen/xenbus/xenbus_probe_frontend.c:EXPORT_SYMBOL_GPL(xenbus_register_frontend);
> 
> xen-fbfront already pulls in the module, at least in Linus' tree.
> 
> > Better yet if udev/kudzu figured out this automtically and loaded
> > the modules.
> 
> No workarounds for kernel problems if not absolutely necessary.
> 
> Bastian
> 
> --
> Military secrets are the most fleeting of all.
> 		-- Spock, "The Enterprise Incident", stardate 5027.4
>