ebied...@xmission.com (Eric W. Biederman) writes: >>> In that system ptys simply did not work after boot when I tested >>> associating /dev/ptmx with the first mount of the devpts filesystem. >> >> Assuming userspace isn't broken by that patch, is a fixed association >> with first mount otherwise an acceptable solution for magic /dev/ptmx >> (where /dev/ptmx is not a symlink to /dev/pts/ptmx)? > > I do not believe a fixed association with the first mount is an > acceptable solution for implementing /dev/ptmx in association with > a change to cause mount of devpts to be an independent filesystem. > Such an association fails to be backwards compatible with existing > userspace, and it is extremely fragile.
Ugh. After reviewing the userspace code that mounts devpts we have to do use a magic /dev/ptmx to solve the issue we are trying to solve. The fragility of detecting the primary system devpts seems solvable. CentOS5 and openwrt-15.05 mount devpts, unmount devpts, then mount devpts again. So a rule of mouting the internal devpts if it isn't mounted would work for those. CentOS6 uses switch_root and moves it's early mount of devpts onto the primary root, and then because devpts is also in /etc/fstab tries and fails to mount devpts once more at the same location. Implying newinstance will make that mounting devpts twice. That sounds solvable but I don't see a clean way of detecting that case yet. Ugh. I am going to pound my head up against what is needed to find the primary system mount of devpts for a bit more and see if I can solve that. Otherwise this exercise is pointless. Eric -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
