XiP Filesystem Primps For Linux 2.6.28

nerdyH writes "The Linux-Embedded discussion list has been abuzz the last two days over a flash filesystem designed to support binary code execution (sometimes called XIP, or "execute-in-place"). When combined with forthcoming "Phase Change Memory" products from Intel/ST JV Numonyx, the "Advanced XiP Filesystem" (AXFS) could radically change Linux systems of all kinds, replacing Flash, hard drives, and even DRAM with a single chunk of low-cost, non-volatile memory that can both store files and serve as a platform for program execution."

Comments

Re:Interesting question....

[kasperd]

As processor caches increase, could you use this to run the kernel from the processor caches?

That idea doesn't really have anything to do with XiP support in the file system. You could run the kernel directly from flash as well. And since that is probably simpler, I'd be surprised if that isn't already done. As for running everything from the CPU cache, that is not controlled by the kernel but rather by the CPU itself. And it will try to use the cache for the mostly used parts of memory regardless of whether it is kernel code or not. Of course since the CPU caches are constrained by the number of gates used as well as the number of nanoseconds used to make a decision, they obviously can't always use the caches optimally, but caching all of the kernel wouldn't be optimal either, since there are some rarely used code paths in the kernel.