On a machine using fbdev for X (a Xen guest in this case) with the xorg.conf as
generated via anaconda, FbBpp is set to 24 -- without an xorg.conf, it's set to
32.  32 is correct.

I'll attach logs from with xorg.conf and without

Created attachment 134944 [details]
log from not-working case (with xorg.conf)

Created attachment 134945 [details]
xorg.conf created by anaconda

Note that adding 'DefaultFbBpp 32' to the screen section also makes things work

Hacked the fbdev driver to not have this behavior, but perhaps with other less
than ideal consequences.

Would it make sense to actually set the preferred depth flags based on what the
fbbpp for the actual fbdev device is?

I think so, yes.

Since this bugzilla report was filed, there have been several major updates,
which may have resolved this issue. Users who have experienced this problem are
encouraged to upgrade their system to the latest version of their distribution
available.

Please, if you experience this problem on the up-to-date system, let us now in
the comment for this bug, or whether the upgraded system works for you.

If you won't be able to reply in one month, I will have to close this bug as
INSUFFICIENT_DATA. Thank you.

We're still just carrying the hack and haven't fixed fbdev correctly

Based on the date this bug was created, it appears to have been reported
against rawhide during the development of a Fedora release that is no
longer maintained. In order to refocus our efforts as a project we are
flagging all of the open bugs for releases which are no longer
maintained. If this bug remains in NEEDINFO thirty (30) days from now,
we will automatically close it.

If you can reproduce this bug in a maintained Fedora version (7, 8, or
rawhide), please change this bug to the respective version and change
the status to ASSIGNED. (If you're unable to change the bug's version
or status, add a comment to the bug and someone will change it for you.)

Thanks for your help, and we apologize again that we haven't handled
these issues to this point.

The process we're following is outlined here:
http://fedoraproject.org/wiki/BugZappers/F9CleanUp

We will be following the process here:
http://fedoraproject.org/wiki/BugZappers/HouseKeeping to ensure this
doesn't happen again.

This bug has been in NEEDINFO for more than 30 days since feedback was
first requested. As a result we are closing it.

If you can reproduce this bug in the future against a maintained Fedora
version please feel free to reopen it against that version.

The process we're following is outlined here:
http://fedoraproject.org/wiki/BugZappers/F9CleanUp