AXFS, Advanced Execute In Place Filesystem
Submitted by srlinuxx on Fri, 08/22/2008 - 03:51.
"I'd like to get a first round of review on my AXFS filesystem," began Jared Hulbert, describing his new Advanced XIP File System for Linux. XIP stands for eXecute-In-Place. The new filesystem received quite a bit of positive feedback. Jared offered the following description:
"This is a simple read only compressed filesystem like Squashfs and cramfs. AXFS is special because it also allows for execute-in-place of your applications. It is a major improvement over the cramfs XIP patches that have been floating around for ages."
S390 in netbooks ? L2 cache remapped for execution area ?
AXIP seemed to be designed for PC, but could be more suitable for mainframe architecture which now exists in netbooks(CPU/upto 2mb L2 cache/nand/USB) interestingly.
The L2 cache is larger than the original PC with 456kB execution area which is contiguous.
It has to be remapped above address 100 in L2 cache. 64kB for operating system, 256kB for apps in pages(4kB) from squashfs. 64kB for swap prefetched from nand? Total 384 kB L2 cache mapped.
Firefox has to be executed in an execution area in nand, same as using the 64 kB FAT table in drams above 1 mB boundary in PC?
XiP filesystem primps for Linux 2.6.28
linuxdevices.com: 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, the "Advanced XiP Filesystem" (AXFS) could radically change the way Linux is embedded on consumer devices.
The AXFS project is led by Jared Hulbert, who works for Numonyx. A joint venture of Intel, STMicroelectronics, and Francisco Partners, Numonyx was founded in March of this year to commercialize "phase change memory (PCM)," among other opportunities in the non-volatile memory market.
More Here
Execution in place has to be done by netbook manufacturers ?
First, it can not be in place of devices yet to be developed. Meaning phase change memory may have problems yet unforeseen.
Squashfs compresses frequently used Linux kernel files. Its ratio is 3.5. Linux typically uses 4.5 million lines of codes in the kernels. Netbooks using QNX will only use 750,000 lines of codes(100 bytes per file). Using machine language will be even shorter in lines of codes(just mouse click on binary codes to the cpu).
Execution in place means it can use ddr above the 1 mB boudary as if it is a hdd with FAT table. It can use virtual memory in hdd. it can use any memory in any storage devices. Beware the codes are not bloated to satisfy phase change memory deficiencies or flash transistor life expectancy.
So, merge into kernel 2.6.28 maybe premature. I hope Asus will be doing instant-on and execution in nand or nor flash cards. Eliminating ddr will surely speed up their netbooks faster than the full blown Laptops with ddr burden of slow FSB.
Whether ASUS is good at machine language or not, only time will tell? But after Linux is considered too slow; QNX can be used, before going straight to machine language codes from scratch??
Thanks for pushing the envelop on netbook architecture for new computer technology improvements.