linux-kernel - Re: [PATCH 6/10] lguest code: the little linux hypervisor.

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Date:	Fri, 09 Feb 2007 22:00:12 +1100
From:	Rusty Russell <rusty@...tcorp.com.au>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	lkml - Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Andi Kleen <ak@....de>,
	virtualization <virtualization@...ts.osdl.org>,
	Paul Mackerras <paulus@...ba.org>,
	Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [PATCH 6/10] lguest code: the little linux hypervisor.

On Fri, 2007-02-09 at 01:35 -0800, Andrew Morton wrote:
> On Fri, 09 Feb 2007 20:20:27 +1100 Rusty Russell <rusty@...tcorp.com.au> wrote:
> 
> > +#define log(...)					\
> > +	do {						\
> > +		mm_segment_t oldfs = get_fs();		\
> > +		char buf[100];				\
> > +		sprintf(buf, "lguest:" __VA_ARGS__);	\
> > +		set_fs(KERNEL_DS);			\
> > +		sys_write(1, buf, strlen(buf));		\
> > +		set_fs(oldfs);				\
> > +	} while(0)
> 
> Due to gcc shortcomings, each instance of this will chew an additional 100
> bytes of stack.  Unless they fixed it recently.  Is a bit of a timebomb.  I
> guess ksaprintf() could be used.
> 
> It also looks a bit, umm, innovative.

It's also unused 8)

It's an extremely useful macro for doing grossly invasive logging of the
guest.  I'll drop it if you prefer.

Cheers,
Rusty.

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