Array Allocation

Lprogster · Post by **Lprogster** » Tue May 08, 2007 10:08 am

Hey everyone

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Thank you,
Lster

mathematician · Post by **mathematician** » Tue May 08, 2007 1:54 pm

Quite possibly I am misunderstanding, but wouldn't you necessarily get a page fault if you tried to write to an area of memory without first making an entry in a page table (saying that the relevant page is present)?

Combuster · Post by **Combuster** » Tue May 08, 2007 2:10 pm

where are you defining that array? If you do that on the stack (i.e. inside a function) you can run out of stack space and suffer the consequences

Lprogster · Post by **Lprogster** » Tue May 08, 2007 2:24 pm

...

Thanks,
Lster

Combuster · Post by **Combuster** » Tue May 08, 2007 3:00 pm

gcc will put the array on the stack, somewhere within the functions stack frame. The address itself is simple to get:

unsigned int address = (unsigned int) &(array[0]);

nevertheless, its bad practice to create large arrays on the stack in kernel code. Even a set of small arrays can quickly overflow the stack. Using things other than (unsigned) char will only make matters worse by several factors. Unless you know for sure the array will always fit within the stack, do not allocate it there.