Disabling L1 D-cache and side effects

[Tirumala Reddy Marri]

Ben,
  Thanks for the response. I am wondering how user space would get
affected by absence of L1 Dcache.
Thanks,
Marri

-----Original Message-----
From: Benjamin Herrenschmidt [mailto:benh at kernel.crashing.org] 
Sent: Tuesday, September 30, 2008 12:16 AM
To: Tirumala Reddy Marri
Cc: Olof Johansson; linuxppc-dev at ozlabs.org
Subject: RE: Disabling L1 D-cache and side effects

On Mon, 2008-09-29 at 14:38 -0700, Tirumala Reddy Marri wrote:
> Could you please point me to the which does the Critical error 
> (Machine
> Check) recovery. BTW I am successful booting the Linux until rootfs is

> being mounted. It fails to mount the Linux saying that blocks are 
> corrupted in file system. I had to modify lots of initial bring up 
> code to disable D-cache and make sure all TLB's are cache inhibited. 
> Ando also made sure none of the misc_32.S , entry_32.S and head.S 
> makes any references to d-cache.

Why the heck are you doing that btw ? AFAIK, as Olof says, things like
atomic operations will not work, dcbz neither etc... it's likely that
even if you manage to plaster around all of this in the kernel, whatever
userspace code you'll try to run in userspace will blow up too...

Cheers,
Ben.