On 4 March 2013 23:40, Jeffrey Walton wrote: > Hi All, > > I was looking at some slides on OpenSSL and secure memory wiping using > volatile (Slide 36 at > http://www.slideshare.net/guanzhi/crypto-with-openssl). > > I believe GCC's interpretation of the use for 'volatile' is memory > mapped hardware. I think Ian stated it for me some time ago when I was > trying to understand different interpretations among compilers. If > volatile is for memory mapped hardware, why does GCC compile the > following: > > volatile void clean_memory(volatile void* dest, size_t len) > { > volatile unsigned char* p; > for(p = (volatile unsigned char*)dest; len; dest[--len] = 0) > ;; > } This doesn't compile, it dereferences void. Did you mean p[--len] ? > How does a function become a 'volatile' memory mapped object related > to hardware? The function isn't volatile, the return type is. Qualifying void as volatile is meaningless, but allowed by the C grammar.
