[RFC] [PATCH] powerpc: Add MSR_DE to MSR_KERNEL

[Joakim Tjernlund]

Scott Wood <scottwood at freescale.com> wrote on 2013/06/25 02:51:00:
> 
> On Fri, Jul 20, 2012 at 10:37:17AM +0200, Joakim Tjernlund wrote:
> > Zang Roy-R61911 <r61911 at freescale.com> wrote on 2012/07/20 10:27:52:
> > >
> > >
> > >
> > > > -----Original Message-----
> > > > From: 
linuxppc-dev-bounces+tie-fei.zang=freescale.com at lists.ozlabs.org
> > > > [
mailto:linuxppc-dev-bounces+tie-fei.zang=freescale.com at lists.ozlabs.org]
> > > > On Behalf Of Joakim Tjernlund
> > > > Sent: Friday, June 01, 2012 6:36 AM
> > > > To: Wood Scott-B07421
> > > > Cc: linuxppc-dev at ozlabs.org; Dan Malek; Bob Cochran; Support
> > > > Subject: Re: [RFC] [PATCH] powerpc: Add MSR_DE to MSR_KERNEL
> > > >
> > > > It just occurred to me that you guys have this already in your 
Linux SDK so
> > > > it can't be that bad.
> > > No. MSR_DE is ONLY added when using CW debug in SDK.
> > > Roy
> > >
> > 
> > Yes, and I later found that user space debugging is busted if you turn 
on MSR_DE in
> > kernel.
> 
> So, how should we handle the CONFIG_BDI_SWITCH patch?  It seems like it
> should at least have a warning in the kconfig help text that it breaks
> userspace debugging (to the point of causing a kernel oops if it's
> tried).  Or maybe it can deselect CONFIG_PPC_ADV_DEBUG_REGS?
> 
> It'd also be nice to keep things like this, that are a consequence of 
how
> external debug works on e500, separate from the Abatron-specific stuff.
> 

I was hoping the kernel would grow per context handling of MSR_DE. Then 
one could have
MSR_DE on in MSR_KERNEL but off in user space(unless gdb request it on a 
per process basis). 

 Jocke