Re: kern/52440: nouveau blank screen w/some cards after MSI change in 7.99.64

["John D. Baker" <jdbaker%consolidated.net@localhost>]

The following reply was made to PR kern/52440; it has been noted by GNATS.

From: "John D. Baker" <jdbaker%consolidated.net@localhost>
To: gnats-bugs%NetBSD.org@localhost
Cc: 
Subject: Re: kern/52440: nouveau blank screen w/some cards after MSI change
 in 7.99.64
Date: Tue, 4 Feb 2020 12:11:09 -0600 (CST)

 Following the MSI re-enabling for DRM devices generally and nouveau
 specifically, booting a 9.99.45 GENERIC kernel on the machine that
 previously had no problems with nouveau MSI interrupts panics attaching
 the framebuffer console.
 
 The backtrace ran off the screen and attempting to use LShift+PgUp
 faults in DDB rather than scroll back, so this is the last screenful
 of text (hand-transcribed as machine has no serial port):
 
 [...]
 pci_msi_alloc_exact() at netbsd:pci_msi_alloc_exact+0x64
 pci_intr_alloc() at netbsd:pci_intr_alloc+0x152
 nvkm_pci_init() at netbsd:nvkm_pci_init+0x7a
 nvkm_subdev_init() at netbsd:nvkm_subdev_init+0x8d
 nvkm_device_init() at netbsd:nvkm_device_init+0x262
 nvkm_udevice_init() at netbsd:nvkm_udevice_init+0x4b
 nvkm_object_init() at netbsd:nvkm_object_init+0x62
 nvkm_ioctl_new() at netbsd:nvkm_ioctl_new+0x227
 nvkm_ioctl() at netbsd:nvkm_ioctl+0x10a
 nvif_object_init() at netbsd:nvif_object_init+0xb8
 nvif_device_init() at netbsd_nvif_device_init+0x11
 nouveau_drm_load() at netbsd:nouveau_drm_load+0xeb
 drm_dev_register() at netbsd:drm_dev_register+0xa5
 drm_pci_attach() at netbsd:drm_pci_attach+0x19e
 nouveau_pci_attach_real() at netbsd:nouveau_pci_attach_real+0xb1
 config_mountroot_thread() at netbsd:config_mountroot_thread+0x6f
 cpu0: End traceback...
 fatal breakpoint trap in supervisor mode
 trap type 1 code 0 rip 0x ffffffff8021f55d cs 0x8 rflags 0x202 cr2 0 ilevel 0 rsp 0xffff8280bf602900
 curlwp 0xffffabcde3d3c040 pid 0.79 lowest kstack 0xffff8280bf5ff2c0
 Stopped in pid 0.79 (system) at netbsd:breakpoint+0x5:  leave
 db{0}>
 
 Attempting to scroll back with LShift+PgUp produces:
 
 fatal page fault in supervisor mode
 trap type 6 code 0 rip ffffffff8088e48e cs 0x8 rflags 0x10246 cr2 0x78 ilevel 0x8 rsp 0xffff8280bf604210
 curlwp 0xffffabcde3d3c040 pid 0.79 lowest kstack 0xffff8280bf5ff2c0
 kernel: page fault trap, code=0
 Faulted in DDB; continuing...
 db{0}>
 
 This is netboot/NFS-root (and swap), so no crashdump could be saved.
 
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