ARM: stack region-related issue

ARM: stack region-related issue

[antonynpavlov]

Hi, all!

We have common request_sdram_region("stack", ...)
in mem_malloc_resource() (common/memory.c).

But we also have ARM-special request_sdram_region("stack", ...)
inside arm_request_stack() initcall.

In normal situation there is no problem at all.

Here is the 'iomem' log for versatile qemu virtual board:

0x00000000 - 0x03ffffff (size 0x04000000) ram0
0x00c00000 - 0x00ffffff (size 0x00400000) malloc space
0x01000000 - 0x0102d5f3 (size 0x0002d5f4) barebox
0x0102d5f4 - 0x0102f307 (size 0x00001d14) barebox data
0x0102f308 - 0x010346db (size 0x000053d4) bss
0x03ff8000 - 0x03ffffff (size 0x00008000) stack

But if the board use MEMORY_LAYOUT_FIXED then
we can have a problem.

I enabled CONFIGURABLE_MEMORY_LAYOUT for versatile.
Here is a patch:

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index bd10591..2969b19 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -134,6 +134,7 @@ config ARCH_VERSATILE
 	bool "ARM Versatile boards (ARM926EJ-S)"
 	select CPU_ARM926T
 	select GPIOLIB
+	select HAVE_CONFIGURABLE_MEMORY_LAYOUT
 
 config ARCH_VEXPRESS
 	bool "ARM Vexpres boards"

I have rebuilt barebox with this memory layout:

CONFIG_HAVE_CONFIGURABLE_MEMORY_LAYOUT=y
# CONFIG_MEMORY_LAYOUT_DEFAULT is not set
CONFIG_MEMORY_LAYOUT_FIXED=y
CONFIG_STACK_BASE=0x20000
CONFIG_STACK_SIZE=0x8000
CONFIG_MALLOC_BASE=0x00c00000
CONFIG_MALLOC_SIZE=0x400000

Here is the 'iomem' log for MEMORY_LAYOUT_FIXED:

0x00000000 - 0x03ffffff (size 0x04000000) ram0
0x00020000 - 0x00027fff (size 0x00008000) stack
0x00c00000 - 0x00ffffff (size 0x00400000) malloc space
0x01000000 - 0x0102d61b (size 0x0002d61c) barebox
0x0102d61c - 0x0102f327 (size 0x00001d0c) barebox data
0x0102f328 - 0x010346fb (size 0x000053d4) bss
0x03ff8000 - 0x03ffffff (size 0x00008000) stack

The result is confusing!
We got two stack regions:
 * the first region registered by common code (CONFIG_STACK_BASE=0x20000);
 * the second region registered by ARM-specific code.

-- 
Best regards,
  Antony Pavlov

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Re: ARM: stack region-related issue

[Sascha Hauer]

On Tue, Jul 16, 2013 at 12:30:12PM +0400, antonynpavlov@gmail.com wrote:
> Hi, all!
> 
> We have common request_sdram_region("stack", ...)
> in mem_malloc_resource() (common/memory.c).
> 
> But we also have ARM-special request_sdram_region("stack", ...)
> inside arm_request_stack() initcall.
> 
> In normal situation there is no problem at all.
> 
> Here is the 'iomem' log for versatile qemu virtual board:
> 
> 0x00000000 - 0x03ffffff (size 0x04000000) ram0
> 0x00c00000 - 0x00ffffff (size 0x00400000) malloc space
> 0x01000000 - 0x0102d5f3 (size 0x0002d5f4) barebox
> 0x0102d5f4 - 0x0102f307 (size 0x00001d14) barebox data
> 0x0102f308 - 0x010346db (size 0x000053d4) bss
> 0x03ff8000 - 0x03ffffff (size 0x00008000) stack
> 
> But if the board use MEMORY_LAYOUT_FIXED then
> we can have a problem.
> 
> I enabled CONFIGURABLE_MEMORY_LAYOUT for versatile.
> Here is a patch:
> 
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index bd10591..2969b19 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -134,6 +134,7 @@ config ARCH_VERSATILE
>  	bool "ARM Versatile boards (ARM926EJ-S)"
>  	select CPU_ARM926T
>  	select GPIOLIB
> +	select HAVE_CONFIGURABLE_MEMORY_LAYOUT
>  
>  config ARCH_VEXPRESS
>  	bool "ARM Vexpres boards"
> 
> I have rebuilt barebox with this memory layout:
> 
> CONFIG_HAVE_CONFIGURABLE_MEMORY_LAYOUT=y
> # CONFIG_MEMORY_LAYOUT_DEFAULT is not set
> CONFIG_MEMORY_LAYOUT_FIXED=y
> CONFIG_STACK_BASE=0x20000
> CONFIG_STACK_SIZE=0x8000
> CONFIG_MALLOC_BASE=0x00c00000
> CONFIG_MALLOC_SIZE=0x400000
> 
> Here is the 'iomem' log for MEMORY_LAYOUT_FIXED:
> 
> 0x00000000 - 0x03ffffff (size 0x04000000) ram0
> 0x00020000 - 0x00027fff (size 0x00008000) stack
> 0x00c00000 - 0x00ffffff (size 0x00400000) malloc space
> 0x01000000 - 0x0102d61b (size 0x0002d61c) barebox
> 0x0102d61c - 0x0102f327 (size 0x00001d0c) barebox data
> 0x0102f328 - 0x010346fb (size 0x000053d4) bss
> 0x03ff8000 - 0x03ffffff (size 0x00008000) stack
> 
> The result is confusing!
> We got two stack regions:
>  * the first region registered by common code (CONFIG_STACK_BASE=0x20000);
>  * the second region registered by ARM-specific code.

We should probably get rid of CONFIG_MEMORY_LAYOUT_FIXED completely.
Currently this is used only by some omap xloader configurations, but
this could be changed.

Sascha

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