Re: copy_from_user in drivers/video/fbmem.c

On Fri, 16 Jun 2000, Adrian Cox wrote:

I've just ported the chips driver in 2.2 to the 69030 (now Asiliant, was
Intel, was C&T). I've found that writing to the frame buffer device
fails, because the underlying method in fbmem.c uses copy_from_user(),
and on PowerPC copy_from_user() cannot copy into uncached space.

Which do people think is wrong:
Is copy_from_user() on PPC wrong, because it can't write to uncached
space.
Is fbmem.c wrong, because it tries to use copy_from_user() to memory
mapped IO?

Congratulations! You found a bug in fbmem.c! Fbmem.c should not use direct
memory accesses to access the frame buffer, but must use fb_writel() and
friends instead.

Gr{oetje,eeting}s,

						Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
							    -- Linus Torvalds


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