[U-Boot] [PATCH 2/4] powerpc/85xx:Fix MSR[DE] bit in MSR to support debugger

[Wolfgang Denk]

Dear Prabhakar Kushwaha,

In message <1329296042-28506-1-git-send-email-prabhakar at freescale.com> you wrote:
> Debugger's ability to debug an application is constrained by the
> architecture's debug IP / run-control solution that may impose certain
> requirements for the application itself.
> Similarly, when referring to the e500 and e500v2 architecture, there are two
> basic rules any application has to respect in order to allow full debugging
> support:
>         1. Keep MSR[DE] bit set
>         2. Have a valid opcode that can be fetched from the debug exception
> 	vector [IVPR|IVOR15].
> Here MSR = Machine State register
> 
> This patch makes sure of point "1" and make MSR[DE] bit is set uniformaly
> across the different execution in address space.

Does it make sense to repeast the whole README here?

> diff --git a/arch/powerpc/cpu/mpc85xx/start.S b/arch/powerpc/cpu/mpc85xx/start.S
> index 7bfa2d5..09111e6 100644
> --- a/arch/powerpc/cpu/mpc85xx/start.S
> +++ b/arch/powerpc/cpu/mpc85xx/start.S
> @@ -82,6 +82,11 @@
>  	.globl _start_e500
>  
>  _start_e500:
> +#if defined(CONFIG_E500_V1_V2)
> +/* Enable debug exception */
> +	li	r1,MSR_DE
> +	mtmsr 	r1
> +#endif

Why is this #ifdef needed here?

>  #if defined(CONFIG_SECURE_BOOT) && defined(CONFIG_E500MC)
>  	/* ISBC uses L2 as stack.
> @@ -729,8 +734,8 @@ create_init_ram_area:
>  	msync
>  	tlbwe
>  
> -	lis	r6,MSR_IS|MSR_DS at h
> -	ori	r6,r6,MSR_IS|MSR_DS at l
> +	lis	r6,MSR_IS|MSR_DS|MSR_DE at h
> +	ori	r6,r6,MSR_IS|MSR_DS|MSR_DE at l

And why don;t we need such an #ifdef here?

Also, CONFIG_E500_V1_V2 is undocumented. 

Best regards,

Wolfgang Denk

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