V2GraphicsHandle::from_file() unwrapped/asserted the DumbBuffer
capability, but the display fd is O_NONBLOCK and the graphics driver
often has not finished coming up at handoff time — so from_file failed
with EAGAIN and the assert panicked fbcond. Since fbcond owns the
console and serial mirror, its death froze the whole boot right after
'Performing handoff' with no login prompt.
Return an error from graphics-ipc when the driver does not yet report
DumbBuffer, and have fbcond log-and-return so the handoff is retried
when the driver publishes its surface, instead of panicking.
(Change found as uncommitted work in the fork; committing to preserve
it and unblock the clean-fork build gate.)
Red Bear OS
6694b5af9e