large bss size for sample applications

Sebastian Huber sebastian.huber at
Thu Sep 24 05:48:01 UTC 2015

On 23/09/15 18:31, Jeff Webb wrote:
> On 09/23/2015 07:50 AM, Sebastian Huber wrote:
>> I would use a custom linker command file. Use 
>> c/src/lib/libbsp/arm/xilinx-zynq/startup/ as a template. 
>> In particular the line
>> bsp_section_rwbarrier_align = DEFINED (bsp_section_rwbarrier_align) ? 
>> bsp_section_rwbarrier_align : 1M;
>> is probably not the right thing for you. Maybe use
>> bsp_section_rwbarrier_align = 1;
> Thanks for the detailed information, Sebastian.  I am still digging 
> into this.  So far, I just tried changing bsp_section_rwbarrier_align 
> to 1, but I had the same error.  I will look into this more deeply and 
> reply with some more questions if I can't get it figured out.  It 
> might help to understand why rwbarrier and nocache are required and 
> what is going on here.  I don't think the raspberry pi configuration 
> had these, but I might be mistaken. 

The purpose of the bsp_section_rwbarrier_align is to separate the 
read-only from the read-write sections so that we can use the MMU 
(granularity 1MiB) to protect the read-only sections. There is probably 
a bug in the MMU setup in case the bsp_section_rwbarrier_align is not 
1MiB. You can set the nocache memory to 0 if you don't need this.

Sebastian Huber, embedded brains GmbH

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