Jonathan Campbell wrote: > Every VGA device connected to the PCI bus has resources that are known > to the Linux kernel. One of the memory resources is the video RAM > (always the largest prefetchable resource listed), with the base and > length known to the PCI subsystem. So, all vramfs needs on mount is the > PCI device, and the mountpoint, and it can dole it out to userspace. > Reading and writing is handled with ioremap(). mmap() is handled by > directly mmaping() that VRAM into user-space (just like /dev/fb0). Files > are recorded in system memory as a list of entities with a starting > block and length, so no fragmentation is possible. > > No communication with the GPU is needed to do this, it's possible to use > VRAM this way even on devices that nobody in the system knows how to > talk to. There still seems to be quite a bit of overlap between this and the MTD subsystem... -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.
