MSR loses DE bit in 3.3, BDI2000 cant handle breakpoints?

MSR loses DE bit in 3.3, BDI2000 cant handle breakpoints?

[Joakim Tjernlund]

I cannot make simple break points using BDI2000 work in 3.3, abatro suggests that it
depends on MSR[DE] is cleared by the kernel. With the emulator I can see that
MSR[DE] is off quite often by just stopping at random times and looking at MSR so
it seems like the kernel is turning MSR[DE] off most of the time.
Anyone else having success debugging 3.3 with BDI2000?

This is on a P2010(E500/BOOKE) CPU.

Re: MSR loses DE bit in 3.3, BDI2000 cant handle breakpoints?

[Bob Cochran]

On 05/29/2012 08:00 AM, Joakim Tjernlund wrote:
>
> I cannot make simple break points using BDI2000 work in 3.3, abatro suggests that it
> depends on MSR[DE] is cleared by the kernel. With the emulator I can see that
> MSR[DE] is off quite often by just stopping at random times and looking at MSR so
> it seems like the kernel is turning MSR[DE] off most of the time.
> Anyone else having success debugging 3.3 with BDI2000?
>
> This is on a P2010(E500/BOOKE) CPU.
>
> _______________________________________________
> Linuxppc-dev mailing list
> Linuxppc-dev@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/linuxppc-dev
>

I debug using Freescale CodeWarrior and a USB tap, which also rely on 
MSR[DE] being set.  I develop from the mainline & have a patch set that 
I just recently re-tweaked to support kernel debugging.

If you want, I'll send you my set of patches for the kernel.  They might 
be useful (not sure since I don't use BDI).

Re: MSR loses DE bit in 3.3, BDI2000 cant handle breakpoints?

[Joakim Tjernlund]

Bob Cochran <ppc@mindchasers.com> wrote on 2012/05/29 20:13:21:
>
> On 05/29/2012 08:00 AM, Joakim Tjernlund wrote:
> >
> > I cannot make simple break points using BDI2000 work in 3.3, abatro suggests that it
> > depends on MSR[DE] is cleared by the kernel. With the emulator I can see that
> > MSR[DE] is off quite often by just stopping at random times and looking at MSR so
> > it seems like the kernel is turning MSR[DE] off most of the time.
> > Anyone else having success debugging 3.3 with BDI2000?
> >
> > This is on a P2010(E500/BOOKE) CPU.
> >
> > _______________________________________________
> > Linuxppc-dev mailing list
> > Linuxppc-dev@lists.ozlabs.org
> > https://lists.ozlabs.org/listinfo/linuxppc-dev
> >
>
> I debug using Freescale CodeWarrior and a USB tap, which also rely on
> MSR[DE] being set.  I develop from the mainline & have a patch set that
> I just recently re-tweaked to support kernel debugging.
>
> If you want, I'll send you my set of patches for the kernel.  They might
> be useful (not sure since I don't use BDI).

Thanks, that could be useful, however I just figured something out.
Changing
diff --git a/arch/powerpc/include/asm/reg_booke.h b/arch/powerpc/include/asm/reg_booke.h
index 500fe1d..0cb259b 100644
--- a/arch/powerpc/include/asm/reg_booke.h
+++ b/arch/powerpc/include/asm/reg_booke.h
@@ -37,7 +37,7 @@
 #define MSR_KERNEL     (MSR_ME|MSR_RI|MSR_IR|MSR_DR|MSR_CE)
 #define MSR_USER       (MSR_KERNEL|MSR_PR|MSR_EE)
 #else
-#define MSR_KERNEL     (MSR_ME|MSR_RI|MSR_CE)
+#define MSR_KERNEL     (MSR_ME|MSR_RI|MSR_CE|MSR_DE)
 #define MSR_USER       (MSR_KERNEL|MSR_PR|MSR_EE)
 #endif

Made it work(possible one should change MSR_USER too?)

Question now is why MSR_DE is not on by default? Especially since
BDI2000 is supported by the kernel(CONFIG_BDI_SWITCH=y) is on in my kernel?

 Jocke

Re: MSR loses DE bit in 3.3, BDI2000 cant handle breakpoints?

[Wolfgang Denk]

Dear Bob,

In message <4FC511C1.4050007@mindchasers.com> you wrote:
>
> I debug using Freescale CodeWarrior and a USB tap, which also rely on 
> MSR[DE] being set.  I develop from the mainline & have a patch set that 
> I just recently re-tweaked to support kernel debugging.
> 
> If you want, I'll send you my set of patches for the kernel.  They might 
> be useful (not sure since I don't use BDI).

Please rather submit as a patch on the mailing list.

Thanks.

Best regards,

Wolfgang Denk

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