1 Apr 2005 01:55
Re: MNT_NOEXEC on root filesystem with diskless PXE boot?
Colin Percival <cperciva <at> freebsd.org>
2005-03-31 23:55:37 GMT
2005-03-31 23:55:37 GMT
Tom Alsberg wrote: > Perhaps this should go to -STABLE, I just couldn't be sure. It will get more attention on freebsd-stable <at> , so I'm CCing that list. > We are trying out FreeBSD 5.4-PRERELEASE on diskless clients. I > noticed one problem, being that when setting the LD_LIBRARY_PATH > (or for that matter, LD_PRELOAD, and LD_LIBMAP_DISABLE) environment > variables, nothing will run, as /libexec/ld-elf.so.1 complains: > > Cannot execute objects on / > > According to the sources, this was added in 5.4, and will happen > if / is mounted noexec. Yes, that's quite correct -- although I can't imagine how a bug which caused / to be labelled as "noexec" managed to avoid causing major problems until now. I don't know anything about NFS, but hopefully someone on -stable will be able to work out what's going on from the rest of your email (quoted below). Colin Percival > In this case, / is mounted by the BTX PXE loader over NFS (from a > FreeBSD 5.3 server, right now). "mount" does not show the noexec > flag. However, with the attached little C program I verified that > statfs really returns this flag (0x00000006). >(Continue reading)
I am investigating using snapshots for backup purposes and am running
into similar difficulties, on a 1TB FS it takes over an hour to create
a snapshot, during which time an errant ls or two can lock up the
system. Reading through list archives suggests that the the amount of
time it takes to create the snapshot is not something that is going to
go away and that the issue of an ls in the .snap directory during
snapshot creation lacks a fix and that best current practise is 'try to
avoid that'.
> Yes, this is normal. See the documentation about the snapshots
> implementation (a README in the kernel source tree, I think, and paper
> written by Kirk).
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