Re: [PATCH] ARM: nommu: access ID_PFR1 only if CPUID scheme

From: Greg Ungerer
Date: Thu Mar 23 2017 - 07:49:29 EST


Hi Afzal,

On 23/03/17 20:43, afzal mohammed wrote:
On Fri, Mar 17, 2017 at 10:10:34PM +0530, afzal mohammed wrote:
Greg upon trying to boot no-MMU Kernel on ARM926EJ reported boot
failure. He root caused it to ID_PFR1 access introduced by the
commit mentioned in the fixes tag below.

All CP15 processors need not have processor feature registers, only
for architectures defined by CPUID scheme would have it. Hence check
for it before accessing processor feature register, ID_PFR1.

Fixes: f8300a0b5de0 ("ARM: 8647/2: nommu: dynamic exception base address setting")
Reported-by: Greg Ungerer <gerg@xxxxxxxxxxx>
Signed-off-by: afzal mohammed <afzal.mohd.ma@xxxxxxxxx>

Greg, can i add your Tested-by ?

Absolutely:

Tested-by: Greg Ungerer <gerg@xxxxxxxxxxx>

Thanks for taking care of this.

Regards
Greg


---

Hi Russell,

It would be good to have the fix go in during -rc, as,

1. Culprit commit went in during the last merge window
2. Though nothing supported in mainline is known to be broken, the
original change needs to be modified to be reliable