![]() | |||||||||||||
Messages in this thread |
On Thu, 29 Oct 1998, Andrea Arcangeli wrote: > > This should be clean doable adding a pmd_only() to tell if the pmd does > not need a pte to get the info about phys space. Other arch (and <P5) can > #define pmd_only() 0. There is no way this can be cleanly done. The problem occurs whenever you then try to map or unmap parts of the area to something else: p = mmap(fd, 4M) munmap(p,4k) which anything with this approach will just completely die off, even once you removed the ugly special casing. Basically, anything that wants to do "large page" mappings of a frame buffer needs to use something that isn't standard mmap(). Whether that's a special flag to mmap() or something else is immaterial, but it needs to be done on a VMA basis, not on a page table basis. Because we need to disallow partial unmaps etc. Trying to do this with a standard mmap() and doing page table only tricks is doomed. Don't even try. Linus - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.rutgers.edu Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
| Last update: 2005-03-22 13:45 [from the cache] ©2003-2008 | |||||||||||||