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Re: powerpc/pseries: start rtasd before PCI probing

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  Re: powerpc/pseries: start rtasd before PCI probing Michael Ellerman <mpe@ellerman.id.au> - 2016-06-10 07:20 +0200
    Re: powerpc/pseries: start rtasd before PCI probing Greg Kurz <gkurz@linux.vnet.ibm.com> - 2016-06-10 08:50 +0200

#1419023 — Re: powerpc/pseries: start rtasd before PCI probing

On Mon, 2016-23-05 at 08:28:28 UTC, Greg Kurz wrote:
> A strange behaviour is observed when comparing PCI hotplug in QEMU, between
> x86 and pseries. If you consider the following steps:
> - start a VM
> - add a PCI device via the QEMU monitor before the rtasd has started (for
>   example starting the VM in paused state, or hotplug during FW or boot
>   loader)
> - resume the VM execution
> 
> The x86 kernel detects the PCI device, but the pseries one does not.
> 
> This happens because the rtasd kernel worker is currently started under
> device_initcall, while PCI probing happens earlier under subsys_initcall.
> 
> As a consequence, if we have a pending RTAS event at boot time, a message
> is printed and the event is dropped.
> 
> This patch moves all the initialization of rtasd to arch_initcall, which is
> run before subsys_call: this way, logging_enabled is true when the RTAS
> event pops up and it is not lost anymore.
> 
> The proc fs bits stay at device_initcall because they cannot be run before
> fs_initcall.
> 
> Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
> Tested-by: Thomas Huth <thuth@redhat.com>

Has this been tested on PowerVM ?

cheers

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#1419070

On Fri, 10 Jun 2016 15:18:32 +1000 (AEST)
Michael Ellerman <mpe@ellerman.id.au> wrote:

> On Mon, 2016-23-05 at 08:28:28 UTC, Greg Kurz wrote:
> > A strange behaviour is observed when comparing PCI hotplug in QEMU, between
> > x86 and pseries. If you consider the following steps:
> > - start a VM
> > - add a PCI device via the QEMU monitor before the rtasd has started (for
> >   example starting the VM in paused state, or hotplug during FW or boot
> >   loader)
> > - resume the VM execution
> > 
> > The x86 kernel detects the PCI device, but the pseries one does not.
> > 
> > This happens because the rtasd kernel worker is currently started under
> > device_initcall, while PCI probing happens earlier under subsys_initcall.
> > 
> > As a consequence, if we have a pending RTAS event at boot time, a message
> > is printed and the event is dropped.
> > 
> > This patch moves all the initialization of rtasd to arch_initcall, which is
> > run before subsys_call: this way, logging_enabled is true when the RTAS
> > event pops up and it is not lost anymore.
> > 
> > The proc fs bits stay at device_initcall because they cannot be run before
> > fs_initcall.
> > 
> > Signed-off-by: Greg Kurz <gkurz@linux.vnet.ibm.com>
> > Tested-by: Thomas Huth <thuth@redhat.com>  
> 
> Has this been tested on PowerVM ?
> 
> cheers
> 

No but I shall do it.

Thanks for pointing this out.

--
Greg

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