Subject: Re: atl1 driver corrupting memory?

From: Chuck Ebbert <[email-masked]>
Date: Wed, 25 Jul 2007 17:31:02 -0400

On 07/25/2007 05:22 PM, Chris Snook wrote:
> Chuck Ebbert wrote:
>> I have a report of random errors when using the atl1 driver
>> with kernel 2.6.22.1. Could that be a problem fixed by the
>> recent changes to DMA setup in 2.6.23-rc?
> 
> I hope so.  As far as we can tell the driver and the NIC itself are
> doing the right thing, and the pci layer or chipset is screwing up the
> 64-bit DMA.  This only manifests when physical memory addresses cross
> the 4 GB boundary, and as far as I'm aware atl1 is only used on desktop
> boards, so we don't have a lot of testers.  If someone wants to buy me
> and Jay more RAM so we can test it ourselves, I guess we wouldn't object :)
> 

Our reporter has 8GB of memory in an x86_64 machine.

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=249511

> I favor disabling 64-bit DMA in atl1 until Atheros can track this down
> in the lab.  If we don't get confirmation that this bug is fixed by the
> DMA changes, I think we should revert to 32-bit DMA for 2.6.23. 
> Limiting ourselves to 32-bit DMA on desktop systems is a lot less bad
> than allowing arbitrary memory corruption.
> 

This is what was committed.

http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=3f516c00d416bd39aab6cfb348b68919e295fe23
http://git.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=ef76e3e2505db01f7d4b537854f4a177220c26c8