* Pádraig Brady: > On 09/03/2020 18:51, Paul Eggert wrote: >> On 3/9/20 10:30 AM, Pádraig Brady wrote: >> >>> A very similar "ENOTSUP" problem is being reported with coreutils-8.32 >>> with `mknod -m 666 /dev/random c 1 8` when trying to build Fedora >>> rawhide in a chroot. >>> https://bugzilla.redhat.com/1811038 >> >> I don't understand that bug report. The strace diff you mentioned in >> Comment 4 looks like the new mknod command is working. And yet the >> original bug report says new mknod command is complaining "Operation not >> supported". >> >> Is the problem that some filesystems don't work with the chmod >> /proc/self/fd/NNN trick, and that it worked for you (the strace diff) >> but not for Mohan (the original bug report)? > > Right, the strace is from my working mknod(1) > to show the differences between 8.31 and 8.32. > > I've requested an strace from the failing system.
I guess it's possible that just isn't mounted at this point. The glibc implementation will definitely *not* add racy fallback in case /proc is not available, so this will not work until someone implements the required system call. It's not clear to my why the mknod command would need fchmodat at all. With the -m argument, it should simply set the umask to 0, and pass the mode bits to the mknod function.
