| What | Removed | Added |
|---|---|---|
| CC | v10lator@myway.de |
Comment # 9
on bug 97909
from Thomas Rohloff
(In reply to Nicolai Hähnle from comment #5) > Okay, so I could reproduce this after all with the web demo. > > There is a bug in X-Plane and also questionable behaviour of the driver. The > bug in X-Plane is that it uses GL_AMD_pinned_memory with a size that is not > a multiple of a page; as per the spec, the driver is allowed to reject that, > and we do (apparently unlike the closed source driver...). X-Plane doesn't > check this error condition, and continues rendering, hence the crash, which > would also happen with a simple sequence of: > > glGenBuffers(1, &bo); > glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, bo); > glDrawElements(...); > > Somewhat surprisingly, the OpenGL spec never states that a draw call that > goes outside the element/index buffer should flag a GL_INVALID_OPERATION. > There is also no mention of this in the GL_ARB_robust_buffer_access_behavior > extension, which is surprising. > > The patch you provide may or may not go in the right direction - I'm not > sure. If we want to check that, we should do it in api_validate.c, but I'm > not convinced that we should. Meanwhile, that check wouldn't properly fix > the issue in X-Plane. To work around the bug in X-Plane, you need to run > with: > > MESA_EXTENSION_OVERRIDE=-GL_AMD_pinned_memory ./X-Plane-x86_64 --force_run > > which will work with an unmodified driver. I opened a bug report at X-Plane and will inform you in case they reply. BTW: Should I open a new bug report for the r600 bug (see below) ? Here the message I wrote to the X-Plane devs: Subject: Bug report: Wrog usage of GL_AMD_pinned_memory leads to undefined result on Mesa drivers From= v10lator@myway.de IP= [SNIPPED] Product= XPlane Version= 11.11 OS= Linux Summary= Wrog usage of GL_AMD_pinned_memory leads to undefined behavior on Mesa drivers Description= "The bug in X-Plane is that it uses GL_AMD_pinned_memory with a size that is not a multiple of a page; as per the spec, the driver is allowed to reject that, and we do (apparently unlike the closed source driver...). X-Plane doesn't check this error condition, and continues rendering, hence the crash" - Source: https://bugs.freedesktop.org/show_bug.cgi?id=97909#c5 Similar things as described in the linked bug report are happening on other Mesa drivers, too. For example see this stacktrace from r600: [ 1930.559125] general protection fault: 0000 [#1] PREEMPT SMP [ 1930.559980] Modules linked in: snd_seq_midi snd_usb_audio snd_hwdep snd_usbmidi_lib snd_rawmidi vboxpci(O) vboxnetadp(O) vboxnetflt(O) nfsd vboxdrv(O) [ 1930.560867] CPU: 2 PID: 646 Comm: kworker/2:2 Tainted: G O 4.13.0 #9 [ 1930.561771] Hardware name: To be filled by O.E.M. To be filled by O.E.M./SABERTOOTH 990FX R2.0, BIOS 2901 05/04/2016 [ 1930.562657] Workqueue: events radeon_mn_destroy [ 1930.563588] task: ffffa246244e5b00 task.stack: ffffa5f0409a0000 [ 1930.564509] RIP: 0010:__mutex_lock.isra.1+0x82/0x518 [ 1930.565425] RSP: 0018:ffffa5f0409a3d60 EFLAGS: 00010282 [ 1930.566312] RAX: 800000015e292268 RBX: ffffa2435d99c228 RCX: 800000015e29226f [ 1930.567238] RDX: 800000015e29226f RSI: ffffa246244e5b00 RDI: ffffffffb2a04c10 [ 1930.568174] RBP: ffffa5f0409a3df0 R08: ffffa2435d99c200 R09: 0000000100200007 [ 1930.569124] R10: ffffa5f0409a3e10 R11: ffffa2462c079ac0 R12: ffffa2463ec9c400 [ 1930.570037] R13: ffffa2435d99f9e8 R14: ffffa2463ec98300 R15: 0000000000000002 [ 1930.570982] FS: 0000000000000000(0000) GS:ffffa2463ec80000(0000) knlGS:0000000000000000 [ 1930.571938] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1930.572894] CR2: 0000000000ed7000 CR3: 00000003c8c51000 CR4: 00000000000406e0 [ 1930.573857] Call Trace: [ 1930.574783] ? __slab_free.isra.68+0x7a/0x210 [ 1930.575744] ? __slab_free.isra.68+0x7a/0x210 [ 1930.576698] ? radeon_mn_destroy+0x3a/0x188 [ 1930.577650] ? radeon_mn_destroy+0x3a/0x188 [ 1930.578577] ? process_one_work+0x151/0x2d0 [ 1930.579515] ? worker_thread+0x1f0/0x380 [ 1930.580450] ? kthread+0xf2/0x128 [ 1930.581381] ? process_one_work+0x2d0/0x2d0 [ 1930.582309] ? kthread_create_on_node+0x40/0x40 [ 1930.583195] ? ret_from_fork+0x22/0x30 [ 1930.584100] Code: 85 c0 0f 84 31 02 00 00 65 48 8b 04 25 80 c2 00 00 48 8b 00 a8 08 75 23 e8 dc be 72 ff 49 8b 45 00 48 83 e0 f8 0f 84 3e 02 00 00 <8b> 58 60 e8 ee be 72 ff 85 db 0f 85 33 02 00 00 65 48 8b 04 25 [ 1930.585083] RIP: __mutex_lock.isra.1+0x82/0x518 RSP: ffffa5f0409a3d60 [ 1930.592739] ---[ end trace 397a922d2c74a9bd ]--- [ 1932.388592] sched: RT throttling activated [ 1935.978694] note: kworker/2:2[646] exited with preempt_count 1 Steps= Run X-Plane 11 on Linux with Mesa drivers.
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