linux-kernel - Re: [PATCH] tty/powerpc: fix build break with ehv

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Message-ID: <20110825184655.GB1891@kroah.com>
Date:	Thu, 25 Aug 2011 11:46:55 -0700
From:	Greg KH <greg@...ah.com>
To:	Timur Tabi <timur@...escale.com>
Cc:	sfr@...b.auug.org.au, linux-next@...r.kernel.org,
	linux-kernel@...r.kernel.org, linuxppc-dev@...abs.org
Subject: Re: [PATCH] tty/powerpc: fix build break with ehv_bytechan.c on
 allyesconfig

On Thu, Aug 25, 2011 at 01:02:01PM -0500, Timur Tabi wrote:
> Greg KH wrote:
> > tested doesn't mean that it shouldn't still build properly for other
> > platforms, right?
> 
> The problem is the dependency on MSR_GS, which is defined only for Book-E
> PowerPC chips, not all PowerPC.
> 
> So I gave it some more thought, and technically ePAPR extends beyond Book-E, so
> it's wrong for the driver to depend on anything specific to Book-E.  I've
> removed the code that breaks:
> 
> 	/* Check if we're running as a guest of a hypervisor */
> 	if (!(mfmsr() & MSR_GS))
> 		return;

But don't you really want this type of check at runtime?  What happens
if you load this driver on a machine that is not a guest?  Will things
break?  Shouldn't you still refuse to load somehow?

thanks,

greg k-h
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