Description:

udevadm trigger --action=add --type=devices (part of boot sequence) causes system hang as soon as it touches graphics card. Symptomes:
- screen goes off (both backlight and picture)
- keyboard leds react to keys, but
- no reaction to blindly typed commands
- no reaction on ACPI events (power button, lid close)
- network stops working

(I have made some tests after manually starting network, acpid and syslog and then triggering hang).

I have tried it on three kernels: current as of now versions of standard Arch kernel (3.5.4-1), ck-p4 (Graysky build, 3.5.4-1) and lts (3.0.43-1) with same result; so it does not seem to be kernel fault.

I have not much left to add, as screen goes off, syslog provides no logs during hang, journalctl apparently cannot read its own binary logs since last update, network fails and machine has no serial port, so no message could be read.

Additional info:
* systemd version: 189, package 189-4
* hardware according to lspci: VIA Technologies, Inc. CN700/P4M800 Pro/P4M800 CE/VN800 Graphics [S3 UniChrome Pro] (rev 01)

Workaround (not too pretty):
just add --attr-nomatch=boot_vga to relevant udevadm invocation. Everything works OK then, so probably udevadm has no real reason to harass my unichrome ;)