Colin Watson cjwatson at
Tue Dec 30 13:24:08 UTC 2008

On Mon, Dec 29, 2008 at 11:51:26AM -0700, Tim Gardner wrote:
> Scott James Remnant wrote:
> > On Mon, 2008-12-29 at 11:05 -0700, Tim Gardner wrote:
> >> It appears that changing the kernel config thusly requires
> >> 'pty.legacy_count=N' as a kernel boot parameter for alternate and server
> >> installs.
> >
> > Why do servers need that at all?!

"Alternate and server installs", i.e. d-i. There's nothing
server-specific here.

> > Do you have a bug reference, or has somebody misunderstood the options
> > we're changing here?
> I've not filed a bug report on it yet since I just noticed the problem.
> About the time /sbin/init is launched, the screen clears and
> continuously prints "can't get a pty: no such device or file exists" (or
> something close to that).

This message comes from bterm, the UTF-8 framebuffer terminal used in
d-i. bterm does use Unix98 ptys if available (I patched it to do this
way back in 2004). However, /dev/pts mistakenly wasn't getting mounted,
and therefore it had to fall back to legacy ptys. It looks like it's
been doing this silently at least back to hardy, so I guess we should be
grateful for this change making it obvious! :-)

I fixed it with this udev upload:

udev (124-12) jaunty; urgency=low

  * Mount /dev/pts at the end of /lib/debian-installer/start-udev, as
    Debian's corresponding script does so and bterm needs it (previously it
    was silently falling back to legacy PTYs, which are no longer so readily
    available and are undesirable anyway).

 -- Colin Watson <cjwatson at>  Mon, 29 Dec 2008 20:22:33 +0000

Colin Watson                                       [cjwatson at]

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