On Thursday 09 September 2004 16:31, Geert Uytterhoeven wrote:

quoted

So if PAGE_SIZE is 4096, to allocate 8192 bytes, use order = 1. Note that
there is an upper limit to order, so keep videomemorysize small.

And the upper limit is 128 kiB on most platforms. Hence even 640x480 in 8
bpp won't fit...

Probably you can make a fb_mmap() hook that's compatible with the
vmalloc()'ed frame buffer and thus doesn't suffer from this limitation, but
it will require more code and more knowledge of memory management
internals.

Actually, I discovered that MAX_ORDER in 2.4 is 10 (4MiB) and 11 in 2.6 
(8MiB), so it's probably not as limiting as it seems. However, the 
probability of __get_free_pages() failing at such a high order is very high.

Tony




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