linux-kernel - Re: [PATCH 3/4] rcutorture: Make -soundhw a x86 specific option

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Date:	Thu, 19 May 2016 07:10:13 -0700
From:	"Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>
To:	Josh Triplett <josh@...htriplett.org>
Cc:	Boqun Feng <boqun.feng@...il.com>, linux-kernel@...r.kernel.org,
	linuxppc-dev@...ts.ozlabs.org,
	Steven Rostedt <rostedt@...dmis.org>,
	Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
	Lai Jiangshan <jiangshanlai@...il.com>
Subject: Re: [PATCH 3/4] rcutorture: Make -soundhw a x86 specific option

On Wed, May 18, 2016 at 09:23:10PM -0700, Josh Triplett wrote:
> On Thu, May 19, 2016 at 11:42:23AM +0800, Boqun Feng wrote:
> > The option "-soundhw pcspk" gives me a error on PPC as follow:
> > 
> > qemu-system-ppc64: ISA bus not available for pcspk
> > 
> > , which means this option doesn't work on ppc by default. So simply make
> > this an x86-specific option via identify_qemu_args().
> > 
> > Signed-off-by: Boqun Feng <boqun.feng@...il.com>
> 
> The emulated system for RCU testing does not need sound hardware at all.
> Paul added this option in commit
> 16c77ea7d0f4a74e49009aa2d26c275f7f93de7c to disable the default sound
> hardware, saying that '"-soundhw pcspk" makes the script a bit less
> dependent on odd audio libraries being installed'.  Unfortunately, it
> looks like there isn't a "-soundhw none".  As far as I can tell,
> currently the only way to completely eliminate sound hardware is to pass
> "-nodefaults" and then explicitly specify each desired device; while
> that would solve the issue, it would likely introduce *more*
> hardware-specific command-line options...
> 
> I've filed two feature requests on upstream qemu to make this simpler:
> https://bugs.launchpad.net/qemu/+bug/1583420 and
> https://bugs.launchpad.net/qemu/+bug/1583421 .
> 
> Paul, what did you mean by "dependent on odd audio libraries"?  Did you
> mean in the guest or the host?  And either way, is this something that
> could potentially be solved another way?

If I remember correctly, Ubuntu 14.04 qemu refused to run the guest
without this option, but I don't recall the exact error message.
I chalked it up to my ignorance of qemu, but I would very much welcome
some way to not have to specify irrelevant hardware.  So thank you very
much for filing the bugs!

								Thanx, Paul