Does Xorg server pin composition buffer's MFNs?
rafal at invisiblethingslab.com
Wed Apr 14 11:07:44 PDT 2010
A bit of background: apparently under Linux, the mfn (say, physical address)
of the frame, that holds an usermode page, can change, unless precautions
are made. See http://lists.xensource.com/archives/html/xen-devel/2010-04/msg00514.html
why it might be an issue in certain virtualized environments.
Question 1: does X server (running under Linux), allocate the composition
buffers in an usual way (using malloc() or similar), or does it do anything
fancier in order to make sure the physical address of composition buffers is
stable in time ?
Question 2: Does ever X server schedule a DMA transaction (to graphics card
presumably) from a composition buffer ? (in such case it would make sense to
pin its physical pages).
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