Why bind to LiveCD /proc before building initramfs ? Post: 303001642

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Top Forums UNIX for Beginners Questions & Answers Why bind to LiveCD /proc before building initramfs ? Post 303001642 by Corona688 on Tuesday 8th of August 2017 11:29:22 AM

08-08-2017

Registered User

Quote:

Originally Posted by sreyan32

Imagine I have an unbootable system where I need to update the kernel image using

Code:

update-initramfs

.

I have seen numerous examples online which show the following

Code:

$ mount -t proc none /mnt/ubuntu/proc
$ mount -o bind /dev /mnt/ubuntu/dev
$ mount -o bind /sys /mnt/ubuntu/sys

After that we chroot into the broken OS and then execute the command to update the initramfs.

My questions are as follows-:
[LIST=1][*]Are we binding the /proc and /dev of the Live CD to the broken system ? Or are we binding the /proc and /dev of the broken system to the live cd ?

Neither. /dev and especially /proc are virtual filesystems, which don't show files but rather imaginary kernel things.

So they're neither livecd, nor your broken system, but something belonging to whatever kernel you're running.

These kernel / device interfaces are pretty hard for a system to do without.

Quote:

If building the initramfs is dependent on the information of the OS for which the initramfs is built then won't it contain erroneous information if we build for the Live CD ? That is use the /proc and /dev of the LiveCD ?

It doesn't so much archive them as use them.

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MSDOSFS(5)						      BSD File Formats Manual							MSDOSFS(5)

NAME

     msdosfs -- MS-DOS file system

SYNOPSIS

     options MSDOSFS

DESCRIPTION

     The msdosfs driver will permit the FreeBSD kernel to read and write MS-DOS based file systems.

     The most common usage follows:

	   mount -t msdosfs /dev/ada0sN /mnt

     where N is the partition number and /mnt is a mount point.  Some users tend to create a /dos directory for msdosfs mount points.  This helps
     to keep better track of the file system, and make it more easily accessible.

     It is possible to define an entry in /etc/fstab that looks similar to:

     /dev/ada0sN	     /dos    msdosfs	     rw      0	     0

     This will mount an MS-DOS based partition at the /dos mount point during system boot.  Using /mnt as a permanent mount point is not advised
     as its intention has always been to be a temporary mount point for floppy and ZIP disks.  See hier(7) for more information on FreeBSD direc-
     tory layout.

SEE ALSO

     mount(2), unmount(2), mount(8), mount_msdosfs(8), umount(8)

AUTHORS

     This manual page was written by Tom Rhodes <trhodes@FreeBSD.org>.

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								  October 1, 2013							       BSD