I'll try to help.... On Mon, Nov 2, 2009 at 4:56 PM, Shameem Ahamed <shameem.ahamed@xxxxxxxxx> wrote: > Hi, > > I know that "When a process is created virtual address is allocated for the process, and the virtual addresses will be dynamically created upon request." > I think it's not the virtual address that is created, but the Virtual Memory Area. Then, addresses are assigned to this VMA. Whether the VMA contains page frame or not, that's another case. > How this virtual memory is allocated by kernel. Is it random ?. Can two process have same virtual memory addresses?. Depends on how it is requested. For example, if the VMA is created with MAP_FIXED flags, then the kernel with create the VMA with the start address exactly like you requested. Of course, if another VMA exists at the the same address, it will fail. Other than that, most likely for anonymous mapping, it is random. However, if you take a look very carefully, it would be somewhere between 0x08000000 and slightly below bottom of stack (0xc000000 minus something). For file backed mapping, especially code segment and library, kernel will get a clue from the dynamic loader. If you analyze a binary, let's say /bin/cat using readelf -S, you'll see that ELF denotes where those parts of code need to be loaded and mapped in virtual memory Hopefully it will give you better picture... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to ecartis@xxxxxxxxxxxx Please read the FAQ at http://kernelnewbies.org/FAQ
