since i finally tracked down the cause of this grief, i figured i'd
share so you can point and laugh.
in upgrading my kernel source and rebuilding a newer kernel,
i somehow ended up deselecting the kernel config option
TMPFS_POSIX_ACL, which is the option that supports ACLs under any
tmpfs mounts, including (argh!) /dev. and ACLs are kind of important
under /dev for things like, well, sound, since ACLs are used to give
users read/write access to all of the sound-related special device
files under /dev/snd for sound to work properly.
how i managed to deselect that option, i have no idea, but once i
isolated the problem to that, it was a simple matter to turn it back
on, rebuild, reboot and -- voila -- i have sound again. but there's
more.
i was kind of miffed at how easy it was to accidentally turn off
that option so i looked in fs/Kconfig to see:
config TMPFS_POSIX_ACL
bool "Tmpfs POSIX Access Control Lists"
depends on TMPFS
select TMPFS_XATTR
select GENERIC_ACL
help
POSIX Access Control Lists (ACLs) support permissions for users and
groups beyond the owner/group/world scheme.
To learn more about Access Control Lists, visit the POSIX ACLs for
Linux website <http://acl.bestbits.at/>.
If you don't know what Access Control Lists are, say N.
where you notice two things.
first, even after you select TMPFS, you can deselect
TMPFS_POSIX_ACL, which strikes me as dangerous. after all, stuff like
sound and other things *requires* ACL support under /dev, so what
would be point of choosing TMPFS without ACLs these days?
and that last help line:
"If you don't know what Access Control Lists are, say N."
yeah, i'm pretty sure that's really, really bad advice these days.
so, in the end, it wasn't a ubuntu issue, it was a straight kernel
issue. grrrrrr ...
rday
--
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Robert P. J. Day Ottawa, Ontario, CANADA
http://crashcourse.ca
Twitter: http://twitter.com/rpjday
LinkedIn: http://ca.linkedin.com/in/rpjday
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