Some considerations

[Marcelo E. Magallon]

 > The current ATI DRI driver doesn't support pbuffers? What is required
 > to get support, or is it a (non)available documentation issue? Also,
 > when pbuffer support is available, can a pbuffer live or move to /
 > from off-videocard memory through agpgart?

 Looking at the GLX specification (1.3, page 21 and 21)

    It is possible to create a GLXPbuffer whose contents may be
    asynchroniously lost at any time

    [...] Thus, the allocation of a GLXPbuffer can fail if there is
    insufficient framebuffer resources.  (Implementations are not
    required to virtualize pbuffer memory) [...]

 Further on it reads (page 23)

    If the GLX_PRESERVED_CONTENTS attribute is set to False in
    attrib_list, then an unpreserved pbuffer is created and the contents
    of the pbuffer may be lost at any time.  If this attribute is not
    specified, or if it is specified as True in attrib_list, then when a
    resource conflict occurs the contents of the pbuffer will be
    preserved (most likely by swapping out portions of the buffer from
    framebuffer to main memory).

 My reading of that is "maybe", meaning, the driver might fail to create
 a preserved pbuffer, but if it does create one, then it has to do
 something to ensure that the pbuffer is preserved when the need arises,
 even if that means moving it to main memory, but it doesn't actually
 have to.

 Marcelo