Why so complicated? If old user space compatibility is required, just use sg_display=0. Sam On 2018-03-07 05:12 AM, Michel Dänzer wrote: > On 2018-03-07 11:04 AM, Christian König wrote: >> Am 07.03.2018 um 10:53 schrieb Michel Dänzer: >>> On 2018-03-07 10:47 AM, Christian König wrote: >>>> See when I tested this the DDX and Mesa where unmodified, so both still >>>> assumed VRAM as placement for scanout BOs, but the kernel forced scanout >>>> BOs into GTT for testing. >>>> >>>> So what happened was that on scanout we moved the VRAM BO to GTT and >>>> after unpinning it on the first command submission which used the BO we >>>> moved it back to VRAM again. >>>> >>>> So as long as we don't want a severe performance penalty when you >>>> combine old userspace with new kernel using a kernel parameter to force >>>> scanout from GTT is not possible. >>> That means we either need to come up with a different workaround for >>> hardware issues transitioning between scanout from VRAM and GTT, or we >>> can't scan out from GTT in that case. >> >> What exactly was the problem with the transition from VRAM to GTT? >> >> I mean what we can rather easily do is check where the existing BO is >> pinned and then always pin into the same domain on page flip. > > Yeah, something like that could work. In which case, all that's needed > is a way for userspace to know that GTT scanout can work, right? With > that information, it can manage the domains of scanout BOs as it wants. > >
