-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 2016-08-15 05:10, [email protected] wrote: > I realize that nVidia's aren't the preferred video card, but (being > divorce-poor) one sometimes has to make do with what one has. :) > > With my on-board nVidia (GeForce7100) and the nouveau driver (on both Tails > and Qubes), things work okay, then suddenly at some random point the screen > gets filled with diagonal line garbage, and things are unresponsive. (The > system seems to still be running, but the screen is pooched and keyboard > seems unresponsive, and no Alt-F1'ing or whatever will get it back. > Processes still seem to be running though, and the ethernet light is > blinking normally as traffic goes in an out, etc.) > > So I put in a PCI card, nVidia Geforce 7300, which seems solid, works > perfectly under Tails. > > However, under Qubes, I experience random screen corruption. > > See: https://i.imgur.com/ovEFgYO.png > > It's usually fewer horizontal lines than in that snap, but I thought I'd > include an extreme example to show the problem. > > It usually happens when the system is a bit busier CPU-wise/memory-wise, > but otherwise functioning fine. Moving the window, or switching to another > window and back, clears up the corruption. > > Screen corruption like that could be a sign of some wild pointer or other > memory management bug, so I thought I'd bring it up. > > The paranoid half of me (okay, okay, I'll admit, it's more than half) > worries it might be some attempted DMA attack. > > (I've been, and continue to be, the subject of some rather high-end > professional hacking over the years, which adds to the concern.) > > I've read about attacks where screen memory is used to stuff code and run > it to escalate privileges. And the nature of the garbage doesn't look like > mis-placed screen stuff, but code or other binary data. Thankfully, if > this is the case, the corruption seems contained to the AppVM. The garbage > never spills outside an AppVm's window. It happens in both Redhat-23 and > Debian-8 based AppVMs. I've never seen evidence of it in dom0/Qubes > Manager and such. > > It realize it's *probably* not an attack, but I'd like to track down the > nature of the problem whether it's a bug or an attack. > > I've read in another thread about video corruption caused by accessing > memory who page has moved, and "echo 0 >> /proc/sys/vm/compact_unevictable_allowed" supposedly helps. At first, I > thought that made a difference, but ultimately, the problem is still > there. > > Any ideas on what I can try, short of giving up and hunting down an ATI > card or the like? (I might try the proprietary nVidia drivers when I get a > chance to compile them. Not comfortable with grabbing binary versions for > obvious reasons.) > > Thanks. You guys rock! >
Looks like it could be this issue: https://github.com/QubesOS/qubes-issues/issues/1028 As you can see from the qubes-builder-github comments, some patches for this are already in the testing repos. You may want to give those a try. - -- Andrew David Wong (Axon) Community Manager, Qubes OS https://www.qubes-os.org -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJXsmoxAAoJENtN07w5UDAwtQQP/RckS46Sz/2A1gVUumsAuTzv wwgW0xOiyZRJI6S6U/YxCAaxek+bTjkpES7qms2ppx13UDvld/sRD3SelkE/GGqz aFKQNmuXMjUf9dZOjbqbF+fz9rzsZKAtIqjchWtWOTlVC3C6YQXhoP3vNPX0xw76 DmuJ7nhGeBnfwUarKkmhkR6azMz7wDLVB981mK0KrDfRtk+zgiE2AXYlECrLSrq7 Hg5ZBIYPBiDvhlcR23xn3dbje4e4F9u6YO67ziD3WkxOmi+lKoOdP/7fib1Bb0Uk QU5sM3Yy7PwFOS5lTLuNAC+SyWlTPRpXp/avJjZx4bE/5Uuf9kKf4+0r7voTM5PZ NO8tg3yDJAYIExMQka+4J7OS//ZXYyIMRyJyi4QcHiz2Ch79uIdvNDV574QY7jkm 04rHBnxslsYjoHfSmDqY1HQuqEX9An3f7OR4upKF+67g9q3rw1QvVSgW9xBbvO4G KcFdH+W85CZYefyTcZK2KFXsg4IZnmC8LWiZVkYEy5aXtLqGmV130LXvE8y+xeJH /NijZ0bd1etAtLmZbdWdqVo5NjjpG2M9Sb8vYGSxaUa0+S69rdezlDXs0kOgL1Wd 6WaFon8jUMMiLdQ7yRszzzWuP/DGp5f8IOfVgVJ/lVRBvbcmyfkLjrt1db8fmKU1 bqEOlqGjLcLNj9sb1BXT =gpn+ -----END PGP SIGNATURE----- -- You received this message because you are subscribed to the Google Groups "qubes-users" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/qubes-users/39a530c3-0b23-7e62-75dc-d6c4fef3231e%40qubes-os.org. For more options, visit https://groups.google.com/d/optout.
