On Wed, 21 Oct 2009, Alexander Best wrote:
hi there,
This is on a 32-bit platform I take it?
just a little mmap(2) related question. running the following code causes a segfault: mmap( (void*)0x1000, 0x80047000, PROT_NONE, MAP_ANON|MAP_FIXED, -1, 0 );
I don't doubt it. You mapped over a big chunk of your address space with memory that's inaccessible (PROT_NONE). This probably includes your program's code. So when the mmap call returns from the kernel and tries to execute the next instruction of your program, it finds that the instruction pointer is pointing to inaccessible memory. Result: segfault. This is quite normal.
What are you actually trying to accomplish with this?
while the following doesn't: mmap( (void*)0x1000, 0xffffffff, PROT_NONE, MAP_ANON|MAP_FIXED, -1, 0 );
Did you check whether the mmap actually succeeded? I bet it didn't. You have a length that isn't a multiple of the page size and wraps around 32 bits. I bet you got an EINVAL, and the mmap call didn't actually do anything.
is this a known problem? seems reproducible on all branches.
Not a problem at all, I suspect. -- Nate Eldredge n...@thatsmathematics.com _______________________________________________ freebsd-hackers@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-hackers To unsubscribe, send any mail to "freebsd-hackers-unsubscr...@freebsd.org"
