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POWhy would changing a structure size, change the size of an executable?
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2013-01-16T19:48:39.113
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Very strange issue I'm working to debug, currently at a loss so I wanted to see if anyone had any thoughts/ideas. There's a define in one of the char drivers in my code base (this is one of many drivers within a uCLinux distribution): <pre><code>#define MAX_BUFSIZE 500 </code></pre> When I build like this I see the output package size: <pre><code>-rw-rw-r-- 1 mike users 1720620 Jan 16 11:00 gcl-kernel.pkg </code></pre> When I change the define to 1000 and rebuild: <pre><code>#define MAX_BUFSIZE 1000 -rw-rw-r-- 1 mike users 2359596 Jan 16 11:17 gcl-kernel.pkg </code></pre> The overall kernel image greatly increases. That one <code>#define</code> was the only change. AFAIK, this should have changed the RAM size of the executable when running, it should not have done anything to the executable's size. So my question: can anyone think of any reason that a structure being modified would change the final image size? <hr> Other analysis/information if you care: I tracked usage of this to one structure defined in a header file: <pre><code>typedef struct { int head; int tail; int status; int active; void * dev[MAX_BUFSIZE]; char free[MAX_BUFSIZE]; canmsg_t data[MAX_BUFSIZE]; int count; } msg_fifo_t; </code></pre> Anytime I change the size of any of those arrays, the executable size changes. Anytime a new object of this type shows up or is removed in the code the executable size changes, ex: <pre><code>extern msg_fifo_t Tx_Bufx[]; extern msg_fifo_t Rx_Buf[]; </code></pre> has a different output executable size then: <pre><code>extern msg_fifo_t Tx_Bufx[]; //extern msg_fifo_t Rx_Buf[]; </code></pre> I've tried but I can't seem to create a smaller version of this issue on my x86 system to debug the problem, it must have something to do with the environment. (coldfire tool chain building for a uCLinux 2.4 kernel).
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<c><linux><size><executable>
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Why would changing a structure size, change the size of an executable?
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