I found that SGI Prism virtual consoles don't work if the system console is defined as ttySG0. The mingetty's start, but nothing appears. If ttySG0 is removed and the console is the graphics head, the virtuals work as expected. Assigning to myself for now. This was observed with the 2.6.12-1.1492_FC5 kernel in the ia64 development repo.
This is SGI Engineering Bug 941467
ia64 is not an officially supported architecture of Fedora, but if you can get the fix for this into the upstream kernel.org kernel, then it will be quickly into the FC5 kernel as we pull from git snapshots regularly. Could you describe what ttySG0 is for? Is the device node for ttySG0 not created? Or possibly is it not created quickly enough for the userspace program that expects it to use it?
ttySG0 is working fine... it is the device for the Altix system console. Even on a prism, I was able to install from ttySG0. The only problem was that virtual consoles on the Prism wouldn't work if console=ttySG0 was present in the kernel parameters.
PS: Hopefully we can get something posted to the community soon; I don't have a feel for the complexity of this problem yet and if the owner will have time to look soon. I'll update the bug when I know more.