> On Iau, 2006-02-09 at 17:32 +0100, Niels Sterrenburg wrote: >> - Do not use swapping in the system >> - Limit Linux memory usage via the mem= option in the kernel command >> line. >> - From MIPS user space: do a mmap for the shared memory area. >> - From MIPS user space: call (our selfwritten) shmemipc driver with the >> request to set the mapped pages to cached (by passing virtual address >> and >> length). >> - From kernel space: find the vma for the supplied virtual address range >> and change cache properties of all pages in that virtual range. > > You don't need to worry about swapping. You can simply mark the pages in > question reserved just as i386 does with the 640K-1Mb hole or since when > a page has a use count it won't swap out, mark it as having a user. In > your case the "user" is the DSP so you just need to account fine Ok, swapping is not (yet) relevant for us, but I'll keep it in mind. > You can provide your own "nopage" method. Good example is > sound/oss/via82cxxx_audio.c > So if I understand correctly I can implement my own nopage routine as part of my driver mmap functionanlity (via initializing vm_ops in mmap). When an mmap on my driver is done to a virtual area for which nopage's exist then my nopage routine is called, right ? Then I can handle tha cache properties while creating the page(s), right ? In the case of the via82cxxx_aucio.c it grabs a dma page, claims it and returns it, right ? If all my above interpretations are correct, how can I then toggle the page caching properties: - on which level should I do that: pte/page level or vma level ? regards, Niels
