Bug#408093: closed by Bastian Blank (Re:Bug#408093: linux-image-2.6.18-3-xen-686: CONFIG_LEGACY_PTY_COUNT=16)
The machine were I reported this problem from, is running Debian Etch + Xen. Everything is installed from packages from the Etch repository, no self-built packages, etc.
In the dom0, there doesn't seem to be a problem with PTY's, eg. Unix PTY's are used.
Output of "who" on dom0 (hosts/usernames hidden ***):
titanium ~ # who
*** pts/3 2007-01-23 15:10 (***)
*** pts/6 2006-12-19 00:51 (***)
On the domU's however, it seems that legacy PTY's are used, causing ugly problems when all of them are in use:
- inability to login through SSH
- inability to create new screen windows
Output of "who" on a domU (hosts/usernames hidden ***):
*** ttyp1 2006-12-19 00:45 (***:S.0)
*** ttyp2 2006-12-19 00:45 (***:S.1)
*** ttyp3 2006-12-22 09:16 (***:S.2)
*** ttyp4 2006-12-19 00:51 (***:S.3)
*** ttypc 2007-01-19 14:43 (***:S.0)
*** ttypd 2007-01-19 14:45 (***:S.1)
*** ttyp5 2007-01-23 15:47 (***)
If nobody wants to use legacy PTY's anymore, then something must be changed to make Xen domU's use Unix PTY's by default instead of legacy ones. If that is not possible, CONFIG_LEGACY_PTY_COUNT=16 *will* cause problems for people who use Xen, and it should be increased either way.
Unfortunately, I don't know of a way to make the domU's use Unix PTY's instead of legacy PTY's. I searched for anything related to Xen and Unix PTY, but I wasn't able to find anything useful yet. Maybe you know a solution... If not, this issue should be investigated further, and this bug reopened and renamed, IMHO.