Hi, I recently stumbled over a test system which showed crashes probably resulting from memory being overwritten randomly. The problem is occurring only in Dom0 when running under Xen. It seems to be present since at least kernel 6.3 (I didn't go back further yet), and it seems NOT to be present in kernel 5.14. I tracked the problem down to the initialization of the graphics card (the problem might surface only later, but at least an early initialization failure made the problem go away). # lspci01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Caicos XTX [Radeon HD 8490 / R5 235X OEM] 01:00.1 Audio device: Advanced Micro Devices, Inc. [AMD/ATI] Caicos HDMI Audio [Radeon HD 6450 / 7450/8450/8490 OEM / R5 230/235/235X OEM]
I had a working .config and one which did produce the crashes, so I narrowed the problem down to detect that the important difference was in the area of firmware loading (the working .config didn't have CONFIG_FW_LOADER_COMPRESS_XZ set, causing firmware loading for the card to fail). This was of course not the real problem, but it caused the card initialization to fail. I manually decompressed the firmware files one by one to see whether the problem would be in the decompressor or probably in the driver of the card. The last step without crash was: # dmesg | grep radeon [ 10.106405] [drm] radeon kernel modesetting enabled. [ 10.106455] radeon 0000:01:00.0: vgaarb: deactivate vga console[ 10.222944] radeon 0000:01:00.0: VRAM: 1024M 0x0000000000000000 - 0x000000003FFFFFFF (1024M used) [ 10.252921] radeon 0000:01:00.0: GTT: 1024M 0x0000000040000000 - 0x000000007FFFFFFF
[ 10.278255] [drm] radeon: 1024M of VRAM memory ready [ 10.295828] [drm] radeon: 1024M of GTT memory ready.[ 10.295867] radeon 0000:01:00.0: Direct firmware load for radeon/CAICOS_pfp.bin succeeded [ 10.330846] radeon 0000:01:00.0: Direct firmware load for radeon/CAICOS_me.bin succeeded [ 10.330858] radeon 0000:01:00.0: Direct firmware load for radeon/BTC_rlc.bin succeeded [ 10.330870] radeon 0000:01:00.0: Direct firmware load for radeon/CAICOS_mc.bin failed with error -2
[ 10.380979] ni_cp: Failed to load firmware "radeon/CAICOS_mc.bin" [ 10.381006] [drm:evergreen_init [radeon]] *ERROR* Failed to load firmware! [ 10.405765] radeon 0000:01:00.0: Fatal error during GPU init [ 10.432107] [drm] radeon: finishing device. [ 10.439179] [drm] radeon: ttm finalized [ 10.463203] radeon: probe of 0000:01:00.0 failed with error -2 And with decompressing radeon/CAICOS_mc.bin I got: # dmesg | grep radeon [ 10.266491] [drm] radeon kernel modesetting enabled. [ 10.266552] radeon 0000:01:00.0: vgaarb: deactivate vga console[ 10.456047] radeon 0000:01:00.0: VRAM: 1024M 0x0000000000000000 - 0x000000003FFFFFFF (1024M used) [ 10.470270] radeon 0000:01:00.0: GTT: 1024M 0x0000000040000000 - 0x000000007FFFFFFF
[ 10.566946] [drm] radeon: 1024M of VRAM memory ready [ 10.576891] [drm] radeon: 1024M of GTT memory ready.[ 10.586971] radeon 0000:01:00.0: Direct firmware load for radeon/CAICOS_pfp.bin succeeded [ 10.611886] radeon 0000:01:00.0: Direct firmware load for radeon/CAICOS_me.bin succeeded [ 10.611909] radeon 0000:01:00.0: Direct firmware load for radeon/BTC_rlc.bin succeeded [ 10.611938] radeon 0000:01:00.0: Direct firmware load for radeon/CAICOS_mc.bin succeeded [ 10.660599] radeon 0000:01:00.0: Direct firmware load for radeon/CAICOS_smc.bin failed with error -2
[ 10.660601] smc: error loading firmware "radeon/CAICOS_smc.bin" [ 10.661676] [drm] radeon: power management initialized[ 10.713666] radeon 0000:01:00.0: Direct firmware load for radeon/SUMO_uvd.bin failed with error -2 [ 10.713668] radeon 0000:01:00.0: radeon_uvd: Can't load firmware "radeon/SUMO_uvd.bin"
[ 10.713669] radeon 0000:01:00.0: failed UVD (-2) init.[ 10.714787] [drm] enabling PCIE gen 2 link speeds, disable with radeon.pcie_gen2=0
[ 10.809213] radeon 0000:01:00.0: WB enabled[ 10.817528] radeon 0000:01:00.0: fence driver on ring 0 use gpu addr 0x0000000040000c00 [ 10.833755] radeon 0000:01:00.0: fence driver on ring 3 use gpu addr 0x0000000040000c0c
[ 10.850330] radeon 0000:01:00.0: radeon: MSI limited to 32-bit [ 10.862154] radeon 0000:01:00.0: radeon: using MSI. [ 10.871930] [drm] radeon: irq initialized. [ 11.062028] [drm] Initialized radeon 2.50.0 20080528 for 0000:01:00.0 on minor 0[ 11.119723] [drm:radeon_dvi_detect [radeon]] *ERROR* DVI-I-1: probed a monitor but no|invalid EDID
[ 11.411370] fbcon: radeondrmfb (fb0) is primary device [ 11.507252] radeon 0000:01:00.0: [drm] fb0: radeondrmfb frame buffer device[ 11.674028] [drm:radeon_dvi_detect [radeon]] *ERROR* DVI-I-1: probed a monitor but no|invalid EDID [ 11.834317] [drm:radeon_dvi_detect [radeon]] *ERROR* DVI-I-1: probed a monitor but no|invalid EDID [ 28.313041] snd_hda_intel 0000:01:00.1: bound 0000:01:00.0 (ops radeon_audio_component_bind_ops [radeon]) [ 44.371991] [drm:radeon_dvi_detect [radeon]] *ERROR* DVI-I-1: probed a monitor but no|invalid EDID [ 44.428068] [drm:radeon_dvi_detect [radeon]] *ERROR* DVI-I-1: probed a monitor but no|invalid EDID
followed by a crash some seconds after the system was up. The crashes vary, but often the kernel accesses non-canonical addresses or tries to map illegal physical addresses. Sometimes the system is just hanging, either with softlockups or without any further signs of being alive. I can easily reproduce the problem, so any debug patches to narrow down the problem are welcome. Juergen
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