Re: [PATCH] Make extended crashkernel= syntax less confusing

[Michael Ellerman <michael@ellerman.id.au>]

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On Wed, 2008-04-30 at 11:29 -0700, Andrew Morton wrote:
> On Wed, 30 Apr 2008 11:36:27 +1000 (EST)
> Michael Ellerman <michael@ellerman.id.au> wrote:
> 
> > The extended crashkernel syntax is a little confusing in the
> > way it handles ranges. eg:
> > 
> >  crashkernel=512M-2G:64M,2G-:128M
> > 
> > Means if the machine has between 512M and 2G of memory the
> > crash region should be 64M, and if the machine has 2G of
> > memory the region should be 64M. Only if the machine has
> > more than 2G memory will 128M be allocated.
> > 
> > Although that semantic is correct, it is somewhat baffling.
> > Instead I propose that the end of the range means the first
> > address past the end of the range, ie: 512M up to but not
> > including 2G.
> > 
> > Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
> > Acked-by: Bernhard Walle <bwalle@suse.de>
> > ---
> > 
> >  kernel/kexec.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/kernel/kexec.c b/kernel/kexec.c
> > index 6782dce..0ab5e33 100644
> > --- a/kernel/kexec.c
> > +++ b/kernel/kexec.c
> > @@ -1217,7 +1217,7 @@ static int __init parse_crashkernel_mem(char 			*cmdline,
> >  		}
> >  
> >  		/* match ? */
> > -		if (system_ram >= start && system_ram <= end) {
> > +		if (system_ram >= start && system_ram < end) {
> >  			*crash_size = size;
> >  			break;
> >  		}
> 
> I'm a bit surprised to see the code being updated but not the
> documentation.  Were they out of sync before or are they out of sync after
> this patch or were they always in sync or what?

Well I think my patch makes the code match the documentation, but it
depends on how you interpret "between xM and yM".

Bernhard's patch to make it explicit is a good idea though.

cheers

-- 
Michael Ellerman
OzLabs, IBM Australia Development Lab

wwweb: http://michael.ellerman.id.au
phone: +61 2 6212 1183 (tie line 70 21183)

We do not inherit the earth from our ancestors,
we borrow it from our children. - S.M.A.R.T Person

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