Re: [PATCH] Load PBL into SRAM

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

On Fri, Jan 31, 2014 at 10:06:10AM +0100, David Vincent wrote:
> This allows to load all the lowlevel init code, including the
> uncompressor, inside SRAM and not just the bare init part. This is
> useful when pbl is used as a first-stage bootloader but is loaded by an
> external firmware.

Just to make sure I understand this correctly: The patch does not make a
code change, all it does is to check that the binary does not get too
big, right?

> +config BAREBOX_MAX_PBL_SIZE
> +	depends on PBL_IMAGE && LOAD_PBL_SRAM
> +	prompt "Maximum pre-bootloader size"
> +	hex
> +	default 0xffffffff
> +	help
> +	  Define the maximum size of pbl
> +	  this will allow your pbl to fit in SRAM as example
> +	  ARCH can overwrite it via ARCH_BAREBOX_MAX_PBL_SIZE

I stumble upon this 'allow', maybe better something like:

On some hardware the ROM code can load the pbl into SRAM, but not the
whole image. This option specifies how big the pbl may get.

What do you think?

Sascha

> +
> +
>  config BAREBOX_MAX_BARE_INIT_SIZE
> -	prompt "Maximum bare_init size"
> +	prompt "Maximum bare_init size" if !LOAD_PBL_SRAM
>  	hex
> +	range 0x0 BAREBOX_MAX_PBL_SIZE if LOAD_PBL_SRAM
> +	default BAREBOX_MAX_PBL_SIZE if LOAD_PBL_SRAM
>  	default 0xffffffff
>  	help
>  	  Define the maximum size of bare_init
> -	  this will allow your bare_init will fit in SRAM as example
> +	  this will allow your bare_init to fit in SRAM as example
>  	  ARCH can overwrite it via ARCH_BAREBOX_MAX_BARE_INIT_SIZE
>  
>  config HAVE_CONFIGURABLE_MEMORY_LAYOUT
> diff --git a/include/asm-generic/barebox.lds.h b/include/asm-generic/barebox.lds.h
> index 6d3a69e..10b0885 100644
> --- a/include/asm-generic/barebox.lds.h
> +++ b/include/asm-generic/barebox.lds.h
> @@ -60,10 +60,22 @@ CONFIG_ARCH_BAREBOX_MAX_BARE_INIT_SIZE < CONFIG_BAREBOX_MAX_BARE_INIT_SIZE
>  #define MAX_BARE_INIT_SIZE CONFIG_BAREBOX_MAX_BARE_INIT_SIZE
>  #endif
>  
> +#if defined(CONFIG_ARCH_BAREBOX_MAX_PBL_SIZE) && \
> +CONFIG_ARCH_BAREBOX_MAX_PBL_SIZE < CONFIG_BAREBOX_MAX_PBL_SIZE
> +#define MAX_PBL_SIZE CONFIG_ARCH_BAREBOX_MAX_PBL_SIZE
> +#else
> +#define MAX_PBL_SIZE CONFIG_BAREBOX_MAX_PBL_SIZE
> +#endif
> +
>  #include <linux/stringify.h>
>  /* use 2 ASSERT because ld can not accept '"size" "10"' format */
>  #define BAREBOX_BARE_INIT_SIZE					\
>  	_barebox_bare_init_size = __bare_init_end - _text;	\
>  	ASSERT(_barebox_bare_init_size < MAX_BARE_INIT_SIZE, "Barebox bare_init size > ") \
> -	ASSERT(_barebox_bare_init_size < MAX_BARE_INIT_SIZE, __stringify(MAX_BARE_INIT_SIZE)) \
> +	ASSERT(_barebox_bare_init_size < MAX_BARE_INIT_SIZE, __stringify(MAX_BARE_INIT_SIZE))
>  
> +#define BAREBOX_PBL_SIZE					\
> +	_barebox_pbl_size = __bss_start - _text;		\
> +	ASSERT(MAX_BARE_INIT_SIZE <= MAX_PBL_SIZE, "bare_init cannot be bigger than pbl") \
> +	ASSERT(_barebox_pbl_size < MAX_PBL_SIZE, "Barebox pbl size > ") \
> +	ASSERT(_barebox_pbl_size < MAX_PBL_SIZE, __stringify(MAX_PBL_SIZE))
> diff --git a/pbl/Kconfig b/pbl/Kconfig
> index dc31357..1edc2d1 100644
> --- a/pbl/Kconfig
> +++ b/pbl/Kconfig
> @@ -34,6 +34,13 @@ config PBL_FORCE_PIGGYDATA_COPY
>  
>  if PBL_IMAGE
>  
> +config LOAD_PBL_SRAM
> +	bool "Load pbl in SRAM"
> +	help
> +	  Load the whole content of the pbl binary into SRAM. This is useful if you
> +	  use the pbl as a first stage bootloader but cannot load the whole binary
> +	  at the same time.
> +
>  config PBL_RELOCATABLE
>  	depends on ARM
>  	bool "relocatable pbl image"
> -- 
> 1.7.10.4
> 
> 
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> 

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