Re: [PATCH 2/3] add CONFIG_PBL_BREAK option

[Sascha Hauer <s.hauer@pengutronix.de>]

On Tue, Jun 04, 2019 at 04:38:52PM +0200, Rouven Czerwinski wrote:
> From: Oleksij Rempel <linux@rempel-privat.de>
> 
> With this option barebox will be build with breakpoint instruction
> in early pbl stage.

It seems not only in early PBL but also during startup of the
uncompressed binary. A bit mor prosa would be nice here.

> 
> Signed-off-by: Oleksij Rempel <linux@rempel-privat.de>
> ---
>  arch/arm/cpu/common.c              | 13 +++++++++++++
>  arch/arm/cpu/start.c               |  2 ++
>  arch/arm/include/asm/barebox-arm.h |  2 ++
>  common/Kconfig                     |  7 +++++++
>  4 files changed, 24 insertions(+)
> 
> diff --git a/arch/arm/cpu/common.c b/arch/arm/cpu/common.c
> index 51fe7ed988..6fe3476aa2 100644
> --- a/arch/arm/cpu/common.c
> +++ b/arch/arm/cpu/common.c
> @@ -30,6 +30,19 @@
>  #define R_ARM_RELATIVE 23
>  #define R_AARCH64_RELATIVE 1027
>  
> +void pbl_barebox_break(void)
> +{
> +	__asm__ __volatile__ (
> +#ifdef CONFIG_PBL_BREAK
> +		"bkpt #17\n"
> +		"nop\n"
> +#else
> +		"nop\n"
> +		"nop\n"
> +#endif
> +	);
> +}
> +
>  /*
>   * relocate binary to the currently running address
>   */
> diff --git a/arch/arm/cpu/start.c b/arch/arm/cpu/start.c
> index 6573c2ef74..6bfc4da34c 100644
> --- a/arch/arm/cpu/start.c
> +++ b/arch/arm/cpu/start.c
> @@ -168,6 +168,8 @@ __noreturn void barebox_non_pbl_start(unsigned long membase,
>  
>  	barrier();
>  
> +	pbl_barebox_break();
> +
>  	pr_debug("memory at 0x%08lx, size 0x%08lx\n", membase, memsize);
>  
>  	arm_endmem = endmem;
> diff --git a/arch/arm/include/asm/barebox-arm.h b/arch/arm/include/asm/barebox-arm.h
> index a11d34923d..12765b7277 100644
> --- a/arch/arm/include/asm/barebox-arm.h
> +++ b/arch/arm/include/asm/barebox-arm.h
> @@ -55,6 +55,7 @@ static inline unsigned long global_variable_offset(void)
>  }
>  
>  void setup_c(void);
> +void pbl_barebox_break(void);
>  void relocate_to_current_adr(void);
>  void relocate_to_adr(unsigned long target);
>  void __noreturn barebox_arm_entry(unsigned long membase, unsigned long memsize, void *boarddata);
> @@ -177,6 +178,7 @@ static inline unsigned long arm_mem_barebox_image(unsigned long membase,
>  				(uint32_t r0, uint32_t r1, uint32_t r2)	\
>  		{							\
>  			__barebox_arm_head();				\
> +			pbl_barebox_break();				\
>  			__##name(r0, r1, r2);				\
>  		}							\
>  		static void NAKED noinline __##name			\
> diff --git a/common/Kconfig b/common/Kconfig
> index ffb7537592..4124857a0a 100644
> --- a/common/Kconfig
> +++ b/common/Kconfig
> @@ -1245,6 +1245,13 @@ config DEBUG_INITCALLS
>  	help
>  	  If enabled this will print initcall traces.
>  
> +
> +config PBL_BREAK
> +	bool "Execute software break on pbl start"
> +	help
> +	  If this enabled, barebox will be compiled with BKPT instruction
> +	  on early pbl init. This option be used only with JTAG debugger!

can, must, should?

It's probably also worth mentioning that the board hangs in the breakpoint
when no debugger is connected.

Sascha

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