From: "Antonino A. Daplas" <adaplas@hotpop.com>
To: linux-fbdev-devel@lists.sourceforge.net,
Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Shivappa Kushtagi <kushtagi@gmail.com>
Subject: Re: Re: Virtual framebuffer driver - mmap problem
Date: Thu, 9 Sep 2004 18:16:51 +0800 [thread overview]
Message-ID: <200409091816.51541.adaplas@hotpop.com> (raw)
In-Reply-To: <Pine.GSO.4.58.0409091029190.10508@waterleaf.sonytel.be>
On Thursday 09 September 2004 16:31, Geert Uytterhoeven wrote:
> >
> > 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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prev parent reply other threads:[~2004-09-09 10:15 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-09-08 13:51 Virtual framebuffer driver - mmap problem Shivappa Kushtagi
2004-09-09 0:31 ` Antonino A. Daplas
2004-09-09 8:31 ` Geert Uytterhoeven
2004-09-09 10:16 ` Antonino A. Daplas [this message]
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