On 3/14/20 10:55 AM, Pierre Labastie via lfs-dev wrote:
Le 14/03/2020 à 16:00, Bruce Dubbs via lfs-dev a écrit :
On 3/14/20 3:41 AM, Pierre Labastie via lfs-dev wrote:
In "6.4 Entering the Chroot Environment", we have:
--------
From this point on, there is no need to use the LFS variable anymore, because
all work will be restricted to the LFS file system. This is because the Bash
shell is told that $LFS is now the root (/) directory.
--------
But it is not true that the bash shell is told anything: the _kernel_ is told
that $LFS is now the root (/) directory for all the processes launched by the
first one (that is, here, "env", which itself launches "bash", which will
launch all the others). I am not sure how to phrase this: something like:
-----
... system. This is because the kernel is told that $LFS is now the root (/)
directory for all the programs run from the current Bash shell.
-----
But I'm sure native English writers can find something better (without
excluding non native of course :)
I think I disagree with your premise. bash IS told where the root directory
is, but there is some interaction with the kernel.
When I enter chroot, env no longer exists. It does an 'exec' and replaces
itself with bash. I took a look at /proc/<pid> for that instance of bash and
in that directory is the pseudo file 'mounts'. That tells me:
/dev/sda6 / ext4 rw,noatime 0 0
which is my /mnt/lfs directory on the host. My interpretation is that this is
a configuration for bash. When doing 'cd /', the kernel looks at this
configuration for the bash instance and uses that to determine what disk
partition (it could be a directory) to use for the head of an absolute path.
In my opinion what we have now is correct.
Thinking a little more about this, what I mean is the following: bash is not
"told" anything, and does not "know" that "/" is $LFS: bash may ask the kernel
to open(2) (or stat(2), or other basic calls) a file by passing the filename
to the kernel, say, /a/file/name, and it is the kernel which resolves that
filename to $LFS/a/file/name, not bash itself.
I'm OK with:
This is because the Bash shell is set up so that $LFS is now the root
(/) directory.
That is: sed /told/set up so/
-- Bruce
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