Created attachment 17150 [details] Configuration file which causes error condition I am attempting to set up a dual-head configuration [xorg-server-1.4.2 with the ati driver]. I have found that there is an infinite loop in the function xf86ProbeOutputModes(), at least with some configurations in xorg.conf . I will attach the xorg.conf which causes the error, and an attempt at a patch to fix the problem. It looks as though the problem is caused by moving "preferred" modes to the start of a doubly-linked list; the problem comes if there is more than one preferred mode, since when we move the current node to the head of the list we will encounter any previous preferred modes again, and repeat the process. The patch gets around this by remembering the "next" pointer before moving the node. However, I'm not sure if this isn't just masking a bigger problem -- are multiple occurrences of preferred modes valid?
Created attachment 17151 [details] Log file corresponding to X process getting stuck in infinite loop
Created attachment 17152 [details] Log file corresponding to working, patched X
Created attachment 17153 [details] Patch which fibes infinite loop
On Mon, Jun 16, 2008 at 15:29:38 -0700, bugzilla-daemon@freedesktop.org wrote: > It looks as though the problem is caused by moving "preferred" modes to the > start of a doubly-linked list; the problem comes if there is more than one > preferred mode, since when we move the current node to the head of the list we > will encounter any previous preferred modes again, and repeat the process. > > The patch gets around this by remembering the "next" pointer before moving the > node. However, I'm not sure if this isn't just masking a bigger problem -- are > multiple occurrences of preferred modes valid? > I think this was fixed in master after 1.4 by adding a userpref flag for xorg.conf modes and having it override the monitor preferred mode. See commits feac0759522cbdc3e61ccfa373df735903c5cb27 and 29e0e180729a4f0cc020985a4de4c8bc4b9c7f5f.
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