elf file sections - contiguous ?

[Altera_Forum]

Hi all , 

Please help me understand the structuring of elf file sections, generated by the nios2 linker. General reading on elf file format did not quite help. So far for the current NIOS application that i am working on, i have seen that the sections are arranged continuously in the memory. The VMA of each section is (VMA of Prev section + size of previous section) Are there any cases where these sections wont be contiguous? For this particualr application, all sections (.text , .rodata , .rwdata) are mapped to sdram. So can i assume that they will be placed contiguously in the memory. Also i use the automatically generated linker script. thanks in advance for any information you can provide

[Altera_Forum]

--- Quote Start ---  originally posted by newbie@Mar 29 2007, 07:39 PM hi all ,         please help me understand the structuring of elf file sections, generated by the nios2 linker. general reading on elf file format did not quite help. so far for the current nios application that i am working on, i have seen that the sections are arranged continuously in the memory. the vma of each section is (vma of prev section + size of previous section) are there any cases where these sections wont be contiguous? for this particualr application, all sections (.text , .rodata , .rwdata) are mapped to sdram. so can i assume that they will be placed contiguously in the memory. also i use the automatically generated linker script. thanks in advance for any information you can provide <div align='right'><{post_snapback}> (index.php?act=findpost&pid=22639)  --- quote end ---    --- Quote End ---    In some cases, it won&#39;t be contiguous. For example you can choose to put the .text in flash, the .rodata and .wrdata in an SDRAM. It only depends on the configuration you put in the system library of your NIOS project.

[Altera_Forum]

Thank you for clarifying my doubt. 

 So, I assume that as long as i don&#39;t change the defualt linker settings or the System Library settings, the sections will remain contiguous.  I do have a couple more questions related to the elf sections :  1) what kind of data does the .exceptions contain ?  2) what does .rwdata contain - is it the section that holds global variables ? ( i could not find the above two sections in .elf format documentation )  3) is there any chance that the sections marked "READ ONLY" (like .exceptions , .text , .rodata ) might get modified at run time ?  I am using the contents of these read only sections to re-program the flash memory , which is why i wanted to know if these sections are subject to change during program execution.    --- Quote Start ---  originally posted by romain53+mar 30 2007, 06:23 am--><div class='quotetop'>quote (romain53 @ mar 30 2007, 06:23 am)</div>  --- quote start ---  <!--quotebegin-newbie@Mar 29 2007, 07:39 PM hi all ,          please help me understand the structuring of elf file sections, generated by the nios2 linker. general reading on elf file format did not quite help. so far for the current nios application that i am working on, i have seen that the sections are arranged continuously in the memory. the vma of each section is (vma of prev section + size of previous section) are there any cases where these sections wont be contiguous? for this particualr application, all sections (.text , .rodata , .rwdata) are mapped to sdram. so can i assume that they will be placed contiguously in the memory. also i use the automatically generated linker script. thanks in advance for any information you can provide <div align='right'><{post_snapback}> (index.php?act=findpost&pid=22639)  --- quote end ---    --- Quote End ---    In some cases, it won&#39;t be contiguous. For example you can choose to put the .text in flash, the .rodata and .wrdata in an SDRAM. It only depends on the configuration you put in the system library of your NIOS project. <div align='right'><{post_snapback}> (index.php?act=findpost&pid=22668)</div> [/b]  --- Quote End ---  

[Altera_Forum]

Hi Nios experts ,  

If any one of you know answers to the questions in the post below, please help . Thanks a bunch.   --- Quote Start ---  originally posted by newbie@Mar 30 2007, 01:24 PM thank you for clarifying my doubt.  so, i assume that as long as i don&#39;t change the defualt linker settings or the system library settings, the sections will remain contiguous.  i do have a couple more questions related to the elf sections :  1) what kind of data does the .exceptions contain ?  2) what does .rwdata contain - is it the section that holds global variables ? ( i could not find the above two sections in .elf format documentation )  3) is there any chance that the sections marked "read only" (like .exceptions , .text , .rodata ) might get modified at run time ?   i am using the contents of these read only sections (actually copy these read only sections from ram at run time) to re-program the flash memory , which is why i wanted to know if these sections are subject to change during program execution.  the .rwdata section is written to flash later, as a second stage. so far it seems to work but i would like to know if this might create any potential problems.    --- quote start ---  originally posted by romain53+mar 30 2007, 06:23 am--><div class='quotetop'>quote (romain53 @ mar 30 2007, 06:23 am)  --- quote end ---    --- quote start ---  <!--quotebegin-newbie@mar 29 2007, 07:39 pm Hi all ,          Please help me understand the structuring of elf file sections, generated by the nios2 linker. General reading on elf file format did not quite help. So far for the current NIOS application that i am working on, i have seen that the sections are arranged continuously in the memory. The VMA of each section is (VMA of Prev section + size of previous section) Are there any cases where these sections wont be contiguous? For this particualr application, all sections (.text , .rodata , .rwdata) are mapped to sdram. So can i assume that they will be placed contiguously in the memory. Also i use the automatically generated linker script. thanks in advance for any information you can provide <div align='right'><{post_snapback}> (index.php?act=findpost&pid=22639)  --- Quote End ---  [/b]  --- Quote End ---    In some cases, it won&#39;t be contiguous. For example you can choose to put the .text in flash, the .rodata and .wrdata in an SDRAM. It only depends on the configuration you put in the system library of your NIOS project. <div align='right'><{post_snapback}> (index.php?act=findpost&pid=22668)</div> [/b]  --- Quote End ---   <div align='right'><{post_snapback}> (index.php?act=findpost&pid=22678)</div> [/b]  --- Quote End ---