On Mon, Apr 20, 2015 at 4:01 PM, Mike Gilbert <flop...@gentoo.org> wrote: > On Mon, Apr 20, 2015 at 3:21 PM, walt <w41...@gmail.com> wrote: >> On 04/19/2015 05:45 PM, Mike Gilbert wrote: >>> On Sun, Apr 19, 2015 at 6:18 PM, walt <w41...@gmail.com> wrote: >> >>>> As a quick-and-dirty way of testing your idea I moved /etc/fstab out of >>>> the way. >>>> >>>> I was surprised to learn that "mount" doesn't care about fstab, and >>>> doesn't even >>>> bother to look for it (when invoked with no arguments). >>>> >>> >>> It reads information from /etc/mtab primarily, as well as >>> /run/mount/utab. Also, if /etc/mtab is a symlink, it reads from >>> /proc/self/mountinfo instead of /etc/mtab. >>> >>> It seems like there is probably some difference in the data it is >>> reading from those files on your system. Maybe post them so we can all >>> have a look? >> >> I really appreciate your help, thanks. Sorry there's so much to read >> through. >> >> I avoided the possible caching problem Francisco mentioned by booting the >> machine >> without an /etc/fstab, so it wound up with only / and swap partitions >> actually >> mounted. >> >> Here are the files that "mount" opened (running with no arguments) that it >> normally would not open: >> >> #cat /proc/cmdline >> BOOT_IMAGE=(hd0,gpt5)/boot/vmlinuz >> root=PARTUUID=345FD3C4-9E1C-49EB-859C-E3A3034325B3 rootwait >> init=/usr/lib64/systemd/systemd >> >> #cat /proc/self/mountinfo >> 12 0 8:21 / / rw,relatime shared:1 - ext4 /dev/root rw,data=ordered > > I think this may be related to having /dev/root appear in > /proc/self/moutinfo. In this case, mount will look for your root > filesystem in /proc/cmdline, and resolve it from there. > > Since your kernel command line has a PARTUUID tag, it probably needs > to scan the partition tables to resolve that. This is mostly a SWAG; I > didn't trace the code to this point.
Also, there was a recent patch changed in gentoo-sources to prevent PARTUUID from appearing in /proc/self/mountinfo. This would explain why this is a "new" behavior for you. https://bugs.gentoo.org/show_bug.cgi?id=467266
