On Thu, Jan 29, 2009 at 08:46:06PM -0800, H. Peter Anvin wrote: > Jonathan Campbell wrote: > > I don't really see the similarity between the MTD subsystem and dividing > > vram up by files. Video cards don't have "erase blocks". And MTD is not > > a filesystem. And the onboard memory mtd driver (map system RAM) only > > handles one fixed region determined at load time. > > > > Vramfs on the other hand determines what resources to use at mount time. > > It supports multiple mounts, one per PCI device, if you want the > > combined VRAM of two VGA cards in your system. > > > > I don't think vramfs would fit well into the MTD subsystem. > > Think about it this way: it is a continuum of facilities. Why is VRAM > different than, say, external DRAM that can only be accessed via a DMA > engine? Now swap the DRAM with NAND flash and perform the same exercise. > > Perhaps the most important reason is that you want to be able to use > this as backing store for swap. Currently the mm doesn't handle swap > which is much faster than filesystems very well, but that should be > possible to address. Also, MTD allows you to map *part* of the VRAM. On my laptop, I only map 56 MB out of the 64 MB of VRAM, which still allows me to use the VGA normally. And BTW, I map this VRAM as a fast swap memory. In fact, I see little use to the VRAMFS for the average user. Still it might have been a nice coding exercice for Jonathan. Willy
