Disabling L1 D-cache and side effects

[Tirumala Reddy Marri]

 Olof,
  Thanks for the response.

  Is there a piece of code in Linux which does the Machine check
recovery and continue normal execution ?
Thanks and Regards,
Marri

-----Original Message-----
From: Olof Johansson [mailto:olof at lixom.net] 
Sent: Monday, September 29, 2008 11:05 AM
To: Tirumala Reddy Marri
Cc: linuxppc-dev at ozlabs.org
Subject: Re: Disabling L1 D-cache and side effects

On Mon, Sep 29, 2008 at 10:05:41AM -0700, Tirumala Reddy Marri wrote:
>  
> Hi,
>   I had to bring up a PPC based SOC with L1 dcache disabled.  I did 
> that and tried to boot Linux using RAMDISK/NFS mount. In RAMDISK I see

> the file system errors. In case of NFS mount I see error saying failed

> to load ld.so library.
>  
>  Could you guys please share thoughts what are the different side 
> effects might be causing this.

There are a number of things you have to be careful about when you
disable caches. Depending on your implementation, you likely can't use
lwarx/stwcx, cache ops will not work, etc. Also, are you 100% sure that
this is caused only by disabling L1D, and not by any other problems with
your silicon?

If you're doing early bringup of you'll have a whole lot of debug work
in front of you, and this mailing list is probably not the best place to
bring your homework.


-Olof