Bug 109680

Summary:	Multiple cards with modesetting results in Segmentation Fault
Product:	xorg	Reporter:	ToBeReplaced
Component:	Driver/AMDgpu	Assignee:	xf86-video-ati maintainers <xorg-driver-ati>
Status:	RESOLVED NOTOURBUG	QA Contact:	Xorg Project Team <xorg-team>
Severity:	normal
Priority:	medium
Version:	unspecified
Hardware:	x86-64 (AMD64)
OS:	Linux (All)
Whiteboard:
i915 platform:		i915 features:

Description ToBeReplaced 2019-02-19 22:05:15 UTC

I am attempting to use modesetting with the following two devices, one AGPU, one Graphics Card. Both cards are working fine if the configuration is modified to omit the other.

10:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Caicos PRO [Radeon HD 7450] (prog-if 00 [VGA controller])
        Subsystem: Micro-Star International Co., Ltd. [MSI] Device 212f
        Flags: bus master, fast devsel, latency 0, IRQ 320
        Memory at e0000000 (64-bit, prefetchable) [size=256M]
        Memory at fe920000 (64-bit, non-prefetchable) [size=128K]
        I/O ports at f000 [size=256]
        Expansion ROM at fe900000 [disabled] [size=128K]
        Capabilities: [50] Power Management version 3
        Capabilities: [58] Express Legacy Endpoint, MSI 00
        Capabilities: [a0] MSI: Enable+ Count=1/1 Maskable- 64bit+
        Capabilities: [100] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
        Capabilities: [150] Advanced Error Reporting
        Kernel driver in use: radeon
        Kernel modules: radeon


38:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Raven Ridge [Radeon Vega Series / Radeon Vega Mobile Series] (rev c8) (prog-if 00 [VGA controller])
        Subsystem: Advanced Micro Devices, Inc. [AMD/ATI] Raven Ridge [Radeon Vega Series / Radeon Vega Mobile Series]
        Flags: bus master, fast devsel, latency 0, IRQ 57
        Memory at c0000000 (64-bit, prefetchable) [size=256M]
        Memory at d0000000 (64-bit, prefetchable) [size=2M]
        I/O ports at d000 [size=256]
        Memory at fe400000 (32-bit, non-prefetchable) [size=512K]
        Expansion ROM at <unassigned> [disabled]
        Capabilities: [48] Vendor Specific Information: Len=08 <?>
        Capabilities: [50] Power Management version 3
        Capabilities: [64] Express Legacy Endpoint, MSI 00
        Capabilities: [a0] MSI: Enable+ Count=1/4 Maskable- 64bit+
        Capabilities: [c0] MSI-X: Enable- Count=3 Masked-
        Capabilities: [100] Vendor Specific Information: ID=0001 Rev=1 Len=010 <?>
        Capabilities: [200] #15
        Capabilities: [270] #19
        Capabilities: [2a0] Access Control Services
        Capabilities: [2b0] Address Translation Service (ATS)
        Capabilities: [2c0] Page Request Interface (PRI)
        Capabilities: [2d0] Process Address Space ID (PASID)
        Capabilities: [320] Latency Tolerance Reporting
        Kernel driver in use: amdgpu
        Kernel modules: amdgpu

Configuration:

Section "ServerLayout" 
    Identifier "Example" 
    Screen 0 "A" 
    Screen 1 "B" 
EndSection 

Section "Device" 
    Identifier "A Card" 
    Driver "modesetting" 
    Screen 0 
    BusID "PCI:16@0:0:0" 
    Option "kmsdev" "/dev/dri/card1" 
    Option "Monitor-DVI-D-1" 
EndSection 

Section "Monitor" 
    Identifier "A Monitor" 
EndSection 

Section "Screen" 
    Identifier "A" 
    Device "A Card" 
    Monitor "A Monitor" 
EndSection 

Section "Device" 
    Identifier "B Card" 
    Driver "modesetting" 
    Screen 1 
    BusID "PCI:56@0:0:0" 
    Option "kmsdev" "/dev/dri/card0" 
    Option "Monitor-HDMI-1" 
EndSection 

Section "Monitor" 
    Identifier "B Monitor" 
EndSection 

Section "Screen" 
    Identifier "B" 
    Device "B Card" 
    Monitor "B Monitor" 
EndSection 

Xorg.log.0:

X.Org X Server 1.20.1
X Protocol Version 11, Revision 0
[430291.775] Build Operating System:  3.10.0-693.17.1.el7.x86_64 
[430291.775] Current Operating System: Linux localhost.localdomain 3.10.0-957.5.1.el7.x86_64 #1 SMP Fri Feb 1 14:54:57 UTC 2019 x86_64
[430291.775] Kernel command line: BOOT_IMAGE=/vmlinuz-3.10.0-957.5.1.el7.x86_64 root=/dev/mapper/centos_localhost-root ro crashkernel=auto rd.lvm.lv=centos_localhost/root rd.lvm.lv=centos_localhost/swap rhgb qui
et
[430291.776] Build Date: 29 January 2019  06:03:26PM
[430291.776] Build ID: xorg-x11-server 1.20.1-5.2.el7_6 
[430291.776] Current version of pixman: 0.34.0
[430291.776]    Before reporting problems, check http://wiki.x.org
        to make sure that you have the latest version.
[430291.776] Markers: (--) probed, (**) from config file, (==) default setting,
        (++) from command line, (!!) notice, (II) informational,
        (WW) warning, (EE) error, (NI) not implemented, (??) unknown.
[430291.776] (==) Log file: "/var/log/Xorg.0.log", Time: Tue Feb 19 15:00:00 2019
[430291.776] (++) Using config directory: "/usr/local/lib/x11test/xorg.conf.d"
[430291.776] (==) Using system config directory "/usr/share/X11/xorg.conf.d"
[430291.776] (==) ServerLayout "Example"
[430291.776] (**) |-->Screen "A" (0)
[430291.776] (**) |   |-->Monitor "A Monitor"
[430291.777] (**) |   |-->Device "A Card"
[430291.777] (**) |-->Screen "B" (1)
[430291.777] (**) |   |-->Monitor "B Monitor"
[430291.777] (**) |   |-->Device "B Card"
[430291.777] (==) Automatically adding devices
[430291.777] (==) Automatically enabling devices
[430291.777] (==) Automatically adding GPU devices
[430291.777] (==) Automatically binding GPU devices
[430291.777] (==) Max clients allowed: 256, resource mask: 0x1fffff
[430291.777] (==) FontPath set to:
        catalogue:/etc/X11/fontpath.d,
        built-ins
[430291.777] (==) ModulePath set to "/usr/lib64/xorg/modules"
[430291.777] (II) The server relies on udev to provide the list of input devices.
        If no devices become available, reconfigure udev or disable AutoAddDevices.
[430291.777] (II) Loader magic: 0x55c6783ce020
[430291.777] (II) Module ABI versions:
[430291.777]    X.Org ANSI C Emulation: 0.4
[430291.777]    X.Org Video Driver: 24.0
[430291.777]    X.Org XInput driver : 24.1
[430291.777]    X.Org Server Extension : 10.0
[430291.778] (II) xfree86: Adding drm device (/dev/dri/card1)
[430291.778] (II) Platform probe for /sys/devices/pci0000:00/0000:00:01.1/0000:10:00.0/drm/card1
[430291.778] (II) Platform PCI device at pci:0000:00:01.1
[430291.778] (II) xfree86: Adding drm device (/dev/dri/card0)
[430291.778] (II) Platform probe for /sys/devices/pci0000:00/0000:00:08.1/0000:38:00.0/drm/card0
[430291.778] (II) Platform PCI device at pci:0000:00:08.1
[430291.786] (--) PCI: (16@0:0:0) 1002:677b:1462:212f rev 0, Mem @ 0xe0000000/268435456, 0xfe920000/131072, I/O @ 0x0000f000/256, BIOS @ 0x????????/131072
[430291.786] (--) PCI:*(56@0:0:0) 1002:15dd:1002:15dd rev 200, Mem @ 0xc0000000/268435456, 0xd0000000/2097152, 0xfe400000/524288, I/O @ 0x0000d000/256, BIOS @ 0x????????/131072
[430291.786] (II) LoadModule: "glx"
[430291.786] (II) Loading /usr/lib64/xorg/modules/extensions/libglx.so
[430291.788] (II) Module glx: vendor="X.Org Foundation"
[430291.788]    compiled for 1.20.1, module version = 1.0.0
[430291.788]    ABI class: X.Org Server Extension, version 10.0
[430291.788] (II) LoadModule: "modesetting"
[430291.788] (II) Loading /usr/lib64/xorg/modules/drivers/modesetting_drv.so
[430291.788] (II) Module modesetting: vendor="X.Org Foundation"
[430291.788]    compiled for 1.20.1, module version = 1.20.1
[430291.788]    Module class: X.Org Video Driver
[430291.788]    ABI class: X.Org Video Driver, version 24.0
[430291.788] (II) modesetting: Driver for Modesetting Kernel Drivers: kms
[430291.788] (--) using VT number 1

[430291.788] (WW) xf86OpenConsole: setpgid failed: Operation not permitted
[430291.788] (WW) xf86OpenConsole: setsid failed: Operation not permitted
[430291.788] (**) modeset(0): claimed PCI slot 16@0:0:0
[430291.788] (II) modeset(0): using /dev/dri/card1
[430291.788] (EE) 
[430291.788] (EE) Backtrace:
[430291.788] (EE) 0: /usr/bin/X (xorg_backtrace+0x55) [0x55c678140185]
[430291.788] (EE) 1: /usr/bin/X (0x55c677f8f000+0x1b4e09) [0x55c678143e09]
[430291.788] (EE) 2: /lib64/libpthread.so.0 (0x7ff8de11e000+0xf5d0) [0x7ff8de12d5d0]
[430291.788] (EE) 3: /usr/lib64/xorg/modules/drivers/modesetting_drv.so (0x7ff8da31d000+0xa144) [0x7ff8da327144]
[430291.788] (EE) 4: /usr/bin/X (0x55c677f8f000+0xb0049) [0x55c67803f049]
[430291.788] (EE) 5: /usr/bin/X (xf86CallDriverProbe+0x4b) [0x55c67801e00b]
[430291.788] (EE) 6: /usr/bin/X (xf86BusConfig+0x46) [0x55c67801e966]
[430291.788] (EE) 7: /usr/bin/X (InitOutput+0x8ac) [0x55c67802bf0c]
[430291.789] (EE) 8: /usr/bin/X (0x55c677f8f000+0x601b0) [0x55c677fef1b0]
[430291.789] (EE) 9: /lib64/libc.so.6 (__libc_start_main+0xf5) [0x7ff8ddd733d5]
[430291.789] (EE) 10: /usr/bin/X (0x55c677f8f000+0x4a4ce) [0x55c677fd94ce]
[430291.789] (EE) 
[430291.789] (EE) Segmentation fault at address 0x2ba
[430291.789] (EE) 
Fatal server error:
[430291.789] (EE) Caught signal 11 (Segmentation fault). Server aborting
[430291.789] (EE) 
[430291.789] (EE) 
Please consult the The X.Org Foundation support 
         at http://wiki.x.org
 for help. 
[430291.789] (EE) Please also check the log file at "/var/log/Xorg.0.log" for additional information.
[430291.789] (EE) 
[430291.789] (EE) Server terminated with error (1). Closing log file.

Comment 1 ToBeReplaced 2019-02-19 22:07:17 UTC

Whoops, forgot to add that I attempted to receive support through #xorg on freenode (no responses), then later at https://superuser.com/questions/1406211/xorg-multi-card-modesetting-configuration-segmentation-fault (no answers). If this is not the appropriate channel for escalation please let me know where would be more appropriate.

Comment 2 Michel Dänzer 2019-02-20 08:44:05 UTC

modesetting driver issues need to be reported at https://gitlab.freedesktop.org/xorg/xserver/issues/new .

That said, does removing the Screen stanzas from Section "Device" help? That is for a so-called "Zaphod" configuration with multiple "Device" and "Screen" sections for the same GPU.

Comment 3 ToBeReplaced 2019-02-20 14:57:55 UTC

Thank you for the quick reply. I'll post an issue there, then close this one.

Removing the Screen sections does not help, unfortunately. I'll post another log in a bit. The end goal is to use it with ZaphodHeads actually, so when moving the issue I'll include the ZaphodHeads lines and a log with those included.

Comment 4 Michel Dänzer 2019-02-20 15:29:48 UTC

(In reply to ToBeReplaced from comment #3)
> Thank you for the quick reply. I'll post an issue there, then close this one.

This one's already resolved, no need to close it.


> Removing the Screen sections does not help, unfortunately.

That's not what I mean. I mean the

 Screen 0/1

stanzas in Section "Device".


> The end goal is to use it with ZaphodHeads actually, so when moving the issue
> I'll include the ZaphodHeads lines and a log with those included.

Like the Screen stanza, Option "ZaphodHeads" is (as the name suggests) only relevant with a Zaphod configuration, not with a single screen per GPU as in your case.

Comment 5 ToBeReplaced 2019-02-20 16:32:59 UTC

Thank you for all of the help. I have come to a resolution based on your hunch about removing Screen lines in the device sections.

The segmentation fault appears to occur if there is no "Screen 0" for a given BusID. The core misunderstanding was that the screen number in the ServerLayout section is *not* related to the screen number in the Device section.

My comment about ZaphodHeads was because I originally had a third screen based off of the second bus id, but I removed it from the configuration since it was not required to cause a Segmentation Fault. My end goal was display :0.0 on one card, :0.1 on another card, and :0.2 on that second card.

A working configuration, with comments for the "surprises" I had is below, in case it is useful for anyone in the future or for improving existing documentaiton.

Section "ServerLayout" 
    Identifier "Example" 
    Screen 0 "A" 
    Screen 1 "B" 
    Screen 2 "C" 
EndSection 

Section "Device" 
    Identifier "A Card" 
    Driver "modesetting" 
    Screen 0 
    BusID "PCI:16@0:0:0" 
    Option "kmsdev" "/dev/dri/card1"
    Option "Monitor-DVI-D-1" 
EndSection 

Section "Monitor" 
    Identifier "A Monitor" 
EndSection 

Section "Screen" 
    Identifier "A" 
    Device "A Card" 
    Monitor "A Monitor" 
EndSection 

Section "Device" 
    Identifier "B Card" 
    Driver "modesetting" 
    Screen 0 # 1st screen for bus, 2nd screen in layout
    BusID "PCI:56@0:0:0" 
    Option "kmsdev" "/dev/dri/card0"
    Option "Monitor-HDMI-1" 
EndSection 

Section "Monitor" 
    Identifier "B Monitor" 
EndSection 

Section "Screen" 
    Identifier "B" 
    Device "B Card" 
    Monitor "B Monitor" 
EndSection 

Section "Device"
    Identifier "C Card"
    Driver "modesetting"
    Screen 1 # 2nd screen for bus, 3rd screen in layout
    BusID "PCI:56@0:0:0"
    Option "kmsdev" "/dev/dri/card0"
    Option "Monitor-HDMI-2"
    Option "ZaphodHeads" "HDMI-2"
EndSection

Section "Monitor"
    Identifier "C Monitor"
EndSection

Section "Screen"
    Identifier "C"
    Device "C Card"
    Monitor "C Monitor"
EndSection

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