Comments on: Computing your stack size http://embeddedgurus.com/stack-overflow/2009/03/computing-your-stack-size/ Thoughts on embedded systems by Nigel Jones Sun, 06 May 2012 10:34:02 +0000 hourly 1 http://wordpress.org/?v=3.3.1 By: Nigel Jones http://embeddedgurus.com/stack-overflow/2009/03/computing-your-stack-size/comment-page-1/#comment-1962 Nigel Jones Fri, 17 Sep 2010 12:56:57 +0000 http://www.gfcdev.org/test-stack/2009/03/01/computing-your-stack-size/#comment-1962 I haven't worked with the LPC2129. I will guess that ROM_start__ is defined to be at 0x44 because the first 0x44 bytes are reserved for the interrupt vector table. I don't know about the RAM - possibly that the first 0x40 bytes are actually consumed by special function registers? As for what to set the various stack sizes to. Well clearly in the first example a lot of the stacks aren't being used. Based on their names it appears that one stack is reserved for a fast interrupt (for example). If you aren't using a fast interrupt then you don't need stack space for it. Conversely if you are using a fast interrupt then you will need to reserve stack space for it. The amount depends on what the fast interrupt handler does. I haven’t worked with the LPC2129. I will guess that ROM_start__ is defined to be at 0×44 because the first 0×44 bytes are reserved for the interrupt vector table. I don’t know about the RAM – possibly that the first 0×40 bytes are actually consumed by special function registers? As for what to set the various stack sizes to. Well clearly in the first example a lot of the stacks aren’t being used. Based on their names it appears that one stack is reserved for a fast interrupt (for example). If you aren’t using a fast interrupt then you don’t need stack space for it. Conversely if you are using a fast interrupt then you will need to reserve stack space for it. The amount depends on what the fast interrupt handler does.

]]> By: GADDOUR zied http://embeddedgurus.com/stack-overflow/2009/03/computing-your-stack-size/comment-page-1/#comment-1960 GADDOUR zied Fri, 17 Sep 2010 10:36:10 +0000 http://www.gfcdev.org/test-stack/2009/03/01/computing-your-stack-size/#comment-1960 I begin to develop a program for LPC2129 with IAR EWARM 5.4 I found that there is a file. ICF when I must to configure for that the linker to the IAR generates. hex specific to my application. i have problem to understand how i can configure its parameters. i found an example of file .ICF in an example of project with IAR. program_in_flash.icf file in leds example provided with iar contains these details. /*-Memory Regions-*/ define symbol __ICFEDIT_region_ROM_start__ = 0x00000044; define symbol __ICFEDIT_region_ROM_end__ = 0x0003FFFF; define symbol __ICFEDIT_region_RAM_start__ = 0x40000040; define symbol __ICFEDIT_region_RAM_end__ = 0x40003FFF; /*-Sizes-*/ define symbol __ICFEDIT_size_cstack__ = 0x200; define symbol __ICFEDIT_size_svcstack__ = 0x0; define symbol __ICFEDIT_size_irqstack__ = 0x100; define symbol __ICFEDIT_size_fiqstack__ = 0x0; define symbol __ICFEDIT_size_undstack__ = 0x0; define symbol __ICFEDIT_size_abtstack__ = 0x0; define symbol __ICFEDIT_size_heap__ = 0x200; according datasheet ROM_start = 0x00000000. why is declared 0x00000044 ? same RAM_start = 0x40000000. I don't understand why is declared 0x40000040 ? and how to initialize the sizes of the stacks? what criteria of choice are initialized these stacks? I find in other examples: they are different parameters of the first example /*-Sizes-*/ define symbol __ICFEDIT_size_cstack__ = 0x2000; define symbol __ICFEDIT_size_svcstack__ = 0x100; define symbol __ICFEDIT_size_irqstack__ = 0x100; define symbol __ICFEDIT_size_fiqstack__ = 0x100; define symbol __ICFEDIT_size_undstack__ = 0x100; define symbol __ICFEDIT_size_abtstack__ = 0x100; define symbol __ICFEDIT_size_heap__ = 0x8000; I do not understand what I put as the size for each stack I begin to develop a program for LPC2129 with IAR EWARM 5.4
I found that there is a file. ICF when I must to configure for that the linker
to the IAR generates. hex specific to my application.
i have problem to understand how i can configure its parameters.

i found an example of file .ICF in an example of project with IAR.

program_in_flash.icf file in leds example provided with iar contains these
details.

/*-Memory Regions-*/
define symbol __ICFEDIT_region_ROM_start__ = 0×00000044;
define symbol __ICFEDIT_region_ROM_end__ = 0x0003FFFF;
define symbol __ICFEDIT_region_RAM_start__ = 0×40000040;
define symbol __ICFEDIT_region_RAM_end__ = 0x40003FFF;
/*-Sizes-*/
define symbol __ICFEDIT_size_cstack__ = 0×200;
define symbol __ICFEDIT_size_svcstack__ = 0×0;
define symbol __ICFEDIT_size_irqstack__ = 0×100;
define symbol __ICFEDIT_size_fiqstack__ = 0×0;
define symbol __ICFEDIT_size_undstack__ = 0×0;
define symbol __ICFEDIT_size_abtstack__ = 0×0;
define symbol __ICFEDIT_size_heap__ = 0×200;

according datasheet ROM_start = 0×00000000. why is declared 0×00000044 ?
same RAM_start = 0×40000000. I don’t understand why is declared 0×40000040 ?

and how to initialize the sizes of the stacks?
what criteria of choice are initialized these stacks?
I find in other examples:

they are different parameters of the first example

/*-Sizes-*/
define symbol __ICFEDIT_size_cstack__ = 0×2000;
define symbol __ICFEDIT_size_svcstack__ = 0×100;
define symbol __ICFEDIT_size_irqstack__ = 0×100;
define symbol __ICFEDIT_size_fiqstack__ = 0×100;
define symbol __ICFEDIT_size_undstack__ = 0×100;
define symbol __ICFEDIT_size_abtstack__ = 0×100;
define symbol __ICFEDIT_size_heap__ = 0×8000;

I do not understand what I put as the size for each stack

]]> By: Nigel Jones http://embeddedgurus.com/stack-overflow/2009/03/computing-your-stack-size/comment-page-1/#comment-1182 Nigel Jones Fri, 25 Jun 2010 12:09:12 +0000 http://www.gfcdev.org/test-stack/2009/03/01/computing-your-stack-size/#comment-1182 Sure. All good linkers allow you to request a call tree report. Different vendors call it different things. In IAR's case, they call it a "static overlay map". What this does is show you all the functions called by a function and the size of the stack at each stage of the call. Here is a <a href="http://embeddedgurus.com/stack-overflow/files/2010/06/Call-Tree.jpg" rel="nofollow">link</a> to an example of the output. By carefully examining this information it is possible to very accurately determine your stack usage. It's also very useful when you are in a pinch for determining where to restructure your code so as to minimize stack usage. For example, you may decide to disable a stack consuming interrupt in the worst case function so as to minimize the peak stack usage. I hope this helps. Sure. All good linkers allow you to request a call tree report. Different vendors call it different things. In IAR’s case, they call it a “static overlay map”. What this does is show you all the functions called by a function and the size of the stack at each stage of the call. Here is a link to an example of the output.

By carefully examining this information it is possible to very accurately determine your stack usage. It’s also very useful when you are in a pinch for determining where to restructure your code so as to minimize stack usage. For example, you may decide to disable a stack consuming interrupt in the worst case function so as to minimize the peak stack usage.
I hope this helps.

]]> By: balaji http://embeddedgurus.com/stack-overflow/2009/03/computing-your-stack-size/comment-page-1/#comment-1181 balaji Fri, 25 Jun 2010 07:03:24 +0000 http://www.gfcdev.org/test-stack/2009/03/01/computing-your-stack-size/#comment-1181 Hi Nigel, Can you give more information on examining the linker output when we are tight on memory. Hi Nigel,

Can you give more information on examining the linker output when we are tight on memory.

]]> By: Nigel Jones http://embeddedgurus.com/stack-overflow/2009/03/computing-your-stack-size/comment-page-1/#comment-144 Nigel Jones Wed, 03 Jun 2009 16:57:49 +0000 http://www.gfcdev.org/test-stack/2009/03/01/computing-your-stack-size/#comment-144 I'm glad you found them useful. I'm glad you found them useful.

]]> By: Scotty http://embeddedgurus.com/stack-overflow/2009/03/computing-your-stack-size/comment-page-1/#comment-143 Scotty Tue, 02 Jun 2009 21:16:16 +0000 http://www.gfcdev.org/test-stack/2009/03/01/computing-your-stack-size/#comment-143 Hey, thanks for the tips. I wish I would've come across this at the beginning of the project. Hey, thanks for the tips. I wish I would’ve come across this at the beginning of the project.

]]> By: Nigel Jones http://embeddedgurus.com/stack-overflow/2009/03/computing-your-stack-size/comment-page-1/#comment-142 Nigel Jones Tue, 31 Mar 2009 12:08:00 +0000 http://www.gfcdev.org/test-stack/2009/03/01/computing-your-stack-size/#comment-142 GregK is quite correct. I touched upon this topic <a HREF="http://www.embeddedgurus.net/stack-overflow/2008/09/efficient-c-tips-4-use-speed.html/" rel="nofollow">here</a>. Like many other developers, I build both a debug and a release target. With the debug target, I typically have optimization set to a minimum. With the release target, I always have optimization set to the maximum. One of the reasons is because changing it can dramatically affect your stack size. Incidentally, I have had the odd occasion in which I have had to switch from speed to size optimization. As and when you do this, it's essential to recompute your stack size. GregK is quite correct. I touched upon this topic here. Like many other developers, I build both a debug and a release target. With the debug target, I typically have optimization set to a minimum. With the release target, I always have optimization set to the maximum. One of the reasons is because changing it can dramatically affect your stack size. Incidentally, I have had the odd occasion in which I have had to switch from speed to size optimization. As and when you do this, it’s essential to recompute your stack size.

]]> By: GregK http://embeddedgurus.com/stack-overflow/2009/03/computing-your-stack-size/comment-page-1/#comment-141 GregK Tue, 24 Mar 2009 21:20:00 +0000 http://www.gfcdev.org/test-stack/2009/03/01/computing-your-stack-size/#comment-141 My advise:Is worth to keep your compiler options constant during development. Small change from -O2 to -O3 could cause big different in stack(s) consumptions. My advise:Is worth to keep your compiler options constant during development. Small change from -O2 to -O3 could cause big different in stack(s) consumptions.

]]> By: Alan Bowens http://embeddedgurus.com/stack-overflow/2009/03/computing-your-stack-size/comment-page-1/#comment-140 Alan Bowens Fri, 06 Mar 2009 07:15:00 +0000 http://www.gfcdev.org/test-stack/2009/03/01/computing-your-stack-size/#comment-140 Nice article on function pointers. I've been using exactly the same state machine approach for a while now, but you give a cogent explanation that I can hand to newbies to quickly get them up to speed. Nice article on function pointers. I’ve been using exactly the same state machine approach for a while now, but you give a cogent explanation that I can hand to newbies to quickly get them up to speed.

]]> By: Nigel Jones http://embeddedgurus.com/stack-overflow/2009/03/computing-your-stack-size/comment-page-1/#comment-139 Nigel Jones Thu, 05 Mar 2009 00:10:00 +0000 http://www.gfcdev.org/test-stack/2009/03/01/computing-your-stack-size/#comment-139 I look forward to hearing what you have to say on this Mike. I look forward to hearing what you have to say on this Mike.

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