On Thu, 26 Aug 2010 01:31:25 +0200, Jonathan Corbet <corbet@xxxxxxx> wrote:
The original OLPC has a camera controller which requires three contiguous, image-sized buffers in memory. That system is a little memory constrained (OK, it's desperately short of memory), so, in the past, the chances of being able to allocate those buffers anytime some kid decides to start taking pictures was poor. Thus, cafe_ccic.c has an option to snag the memory at initialization time and never let go even if you threaten its family. Hell hath no fury like a little kid whose new toy^W educational tool stops taking pictures. That, of course, is not a hugely efficient use of memory on a memory-constrained system. If the VM could reliably satisfy those allocation requestss, life would be wonderful. Seems difficult. But it would be a nicer solution than CMA, which, to a great extent, is really just a standardized mechanism for grabbing memory and never letting go