[mythtv-users] Problems with libvisual (MythMusic) and xmame (MythGame)

Arthur Green arthur at phraction.org
Sun Sep 14 10:13:22 UTC 2008


Timothee Groleau wrote:

[ ... ]

> and here is my xorg.conf:

Thanks for this.

[...]

>>> 2) this issue is not specific to mythtv but I figured some of you may
>>> know: xmame refuses to start (both from mythfrontend and standalone at
>>> the command line), and I can't find what's wrong. I get the following
>>> message: ==========
>>> #xmame.x11 /path/to/rom
>>> [snip]
>>> MIT-SHM Extension Available. trying to use...
>>> Error: failed to create MITSHM block.
>>> video_init failed
>>> ==========
>>>
>>> the shared memory is mounted as follow:
>>> ==========
>>> #mount
>>> shm on /dev/shm type tmpfs (rw,noexec,nosuid,nodev)
>>> ==========
>>>
>>> xmame was emerged with the following use flags:
>>> games-emulation/xmame-0.106  USE="X alsa joystick opengl
>>> sdl -arts -dga -esd -expat -ggi -lirc (-mmx) -net (-svga) -xinerama -xv"
>> Guessing here - maybe there's a permission issue on /dev/shm?
> 
> well, /dev/shm shows as:
> drwxrwxrwt  2 root     root           40 Sep 13 06:53 shm

Not a permission problem then.

It looks as if your X server reports that it supports the MIT-SHM 
extension, but that's not working properly. MIT-SHM sits on top of the 
SysV shared memory system. I think /dev/shm is used for for Posix shared 
memory, not SysV IPC shared memory, so it may not be relevant here.

It may be that the SysV shared memory on your Mythbox is being used by 
something else, so that xmame can't grab what it needs. You can use ipcs 
to see what's being used - this may help diagnose the problem. It's 
useful that you have a machine where xmame works to compare against.

You should be able to increase the amount available with the sysctl 
command, something like:

# kernel.shmmax=<biggernum>

You can make it permanent by setting kernel.shmmax=<biggernum> in 
/etc/sysctl.conf.

Alternatively you could try disabling MIT-SHM in your xmame build. Not 
being a Gentoo user, I don't know how to do this with emerge - I'd just 
bang on the Makefile.

Hope this helps.

> and on my other gentoo box, xmame runs fine, but on that box, I have a 
> dedicated graphic card.
> 
> Tim.
> 

  - Arthur


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