On Tue, Jun 23, 2015 at 5:14 AM, Alan McKinnon <alan.mckin...@gmail.com> wrote: > On 23/06/2015 09:27, Ran Shalit wrote: >> Hello, >> >> I am a beginner with Gentoo. >> I have followed the instruction for the installation, and tried to see >> that I really understand all of them. >> There is the command: >> mount -o bind /dev /mnt/gentoo/dev >> Which I'm not sure I really understand. > > > It's a bind mount, not a regular mount. A regular mount takes a > volume/block device/whatever and mounts it somewhere. > > A bind mount makes a copied mount that is already present on your system > and makes it also available somewhere else. > > You do not want /dev/ and /sys mounted twice - they are core system > directories and bad things can happen if you mount them twice then > change one of them. You get sync issues for one thing. Much much easier > to use bind mounts and potential problems just go away
Err... that's not actually true. You can mount as many instances of devtmpfs as you like; they all point to the same memory and contain the same files. Add a file to one and it will appear in all other instances. This is a distinction between tmpfs and devtmpfs. sysfs is even more straightforward; the kernel maintains all of the files in sysfs, so mounting it multiple times is no issue at all.
