Re: [PATCH] trim memory not covered by WB MTRRs

[Justin Piszcz]

On Tue, 12 Jun 2007, Pavel Machek wrote:

> Hi!
>
> > > > On some machines, buggy BIOSes don't properly setup WB MTRRs to
> > > > cover all available RAM, meaning the last few megs (or even gigs)
> > > > of memory will be marked uncached.  Since Linux tends to allocate
> > > > from high memory addresses first, this causes the machine to be
> > > > unusably slow as soon as the kernel starts really using memory
> > > > (i.e. right around init time).
> > > >
> > > > +	if ((highest_addr >> PAGE_SHIFT) != end_pfn) {
> > > > +		printk(KERN_WARNING "***************\n");
> > > > +		printk(KERN_WARNING "**** WARNING: likely BIOS bug\n");
> > > > +		printk(KERN_WARNING "**** MTRRs don't cover all of "
> > > > +		       "memory, trimmed %ld pages\n", end_pfn -
> > > > +		       (highest_addr >> PAGE_SHIFT));
> > > > +		printk(KERN_WARNING "***************\n");
> > > > +		end_pfn = highest_addr >> PAGE_SHIFT;
> > >
> > > Missing 4K of memory is not worth 4K of junk in syslog per boot. Can
> > > you drop the stars and stop shouting?
> >
> > How missing about 1G of memory?  We already discussed this, and Andi and
> > Venki felt that either a panic or a really obnoxious message was the
> > way to go...
>
> Just use panic, then.
> 									Pavel,
> 	who still thinks anyone missing 1GB of ram will not miss
> 	friendly notice in dmesg, even if it goes without 20 stars.
>
> --
> (english) http://www.livejournal.com/~pavelmachek
> (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

What is wrong with Jesse's patch?  I've been using it for quite a few days 
now, no issues.

Justin.
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