linux-kernel - Re: agpgart: when telling user you'll corrupt his data, at least do it at KERN

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Message-ID: <20080401121323.GB12129@elf.ucw.cz>
Date:	Tue, 1 Apr 2008 14:13:23 +0200
From:	Pavel Machek <pavel@....cz>
To:	Ingo Molnar <mingo@...e.hu>
Cc:	Andi Kleen <andi@...stfloor.org>,
	kernel list <linux-kernel@...r.kernel.org>
Subject: Re: agpgart: when telling user you'll corrupt his data, at least
	do it at KERN_CRIT

On Fri 2008-03-28 15:13:48, Ingo Molnar wrote:
> 
> * Pavel Machek <pavel@....cz> wrote:
> 
> > On Fri 2008-03-28 12:35:28, Ingo Molnar wrote:
> > > 
> > > * Pavel Machek <pavel@....cz> wrote:
> > > 
> > > > IOMMU off means very bad stuff may happen, like data corruption on 
> > > > your hard drives. At least tells users this is serious...
> > > 
> > > ouch. Please at minimum lets turn this into a panic(), but best would be 
> > > to trim memory in this case, hm?
> > 
> > Andi tells me we already fallback to swiotlb, so messages are not on 
> > wrong loglevel; they contain confusing/obsolete text.
> 
> yes that is the theory - but how did your disk get corrupted in 
> practice? ;-)

Well, if you try suspend/resume, without iommu suspend/resume support
(which is not there in some cases), you get nasty data
corruption. ("PCI DMA will does not work").

Then, I saw [obsolete] printk(KERN_ERR) that told me that PCI DMA will
not work, and happily continued to boot.

I'll fix the messages.
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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