On Sat, Jun 22, 2013 at 3:31 AM, Christoph Hellwig <[email protected]> wrote: > On Fri, Jun 21, 2013 at 04:42:41PM -0700, Colin Cross wrote: >> ranges, which John Stultz has been implementing. The second is >> anonymous shareable memory without having a world-writable tmpfs that >> untrusted apps could fill with files. > > I still haven't seen any explanation of what ashmem buys over a shared > mmap of /dev/zero in that respect, btw.
I believe the difference is that ashmem ties the memory to an fd, so it can be passed to another process and mmaped to get to the same memory, but /dev/zero does not. Passing a /dev/zero fd and mmaping it would result in a brand new region of zeroed memory. Opening a tmpfs file would allow sharing memory by passing the fd, but we don't want a world-writable tmpfs. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
