[Bug 599196] Re: ATI Video output cuts off:another workaround

[Luke]

On further experimentation I have  found that the video cutoff is triggered on init by ureadahead, and will re-occur anytime ureadahead is reprofiled or was last profiled on a boot invoking this bug. Since it does not occur with kernels prior to 2.6.34-(anything)-generic, it must be in the kernel somewhere.

Removing /etc/init/ureadahead.conf and /etc/init/ureadahead-other.conf prevents video cutoff, at cost of about 15 sec boot time penalty. Similar time penalty or worse if video cutoff occurs with ureadahead.conf installed.
The boot time penalty of either accepting the video cutoff(which delays the desktop) or removing ureadahead is significant but less that the time lost fixing this after each and every update that reprofiles ureadahead.
If this but gets to the final release, people using the AMD 785 chipset will need to install kernel 2.6.32-(anything)-generic, boot from it once so ureadahead can get a good boot to profile, then boot the normal kernel. This will have to be repeated any time an update reprofiles ureadahead.


 		 	   		  
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ATI Video  output cuts off completely during boot for several seconds
https://bugs.launchpad.net/bugs/599196
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