[gNewSense-users] Recent Success with compile and 10 TB Volume Mount

[Will Hill]

I was recently able to compile a 4.2 kernel on 686 GNewsense and then use it 
to mount a 10 TB encrypted USB drive with a newer ext4 file system.  This 
makes it a little easier to share files between my computers at home and may 
make other devices available to my GNewsense installs.  

The notes I made for myself were:

I'd like to have ext4 partitions made on Stretch work on my TV computer, which 
has a 32bit GNewsense install.  New Ext4_Metadata_Checksums features made 
this difficult.  

I followed my notes for mounting encrypted volumes here,

http://50.80.75.248/photo_album/chron/2018/2018_12_26-mounting_encrypted_drives/

but ran into a checksum difference.  GNewsense has a 3.2 kernel which does not 
seem to be able to read some ext4 attributes, so the device does not mount 
rw.  I got,

"EXT4-fs (dm-3): couldn't mount RDWR because of unsupported optional features 
(400)"

This seems to be due to a new metadata checksum,

https://ext4.wiki.kernel.org/index.php/Ext4_Metadata_Checksums

The recommended cure is to install a new kernel, 3.6 and above and a newer 
version of e2fsprogs.  Unfortunately, I don't have an 686 kernel package 
sitting around, so I'll use the TV install to compile one using the 
instructions from Jessie - see pdf capture.  I just happen  to have 4.2 linux 
libre kernel source, one of the last kernels that does not trigger the 
Coreboot century bug in the versions of Libreboot I have.

I got Gnewsense fakeroot and kernel-package ... and that fails.  falling back 
to older instructions, which also call for build-essential and build-dep 
linux

The I used make config, long and tedious but make xconfig and make menuconfig 
failed me.  

make clean, worked

make deb-pkg failed for lack of bc, apt-get install bc worked, seems to have 
fixed that problem.

... and success one of the best compiles I've done yet.  

willhill@gnewsense:~/src/librelinux$ ls -lrth
total 39M
-rw-r--r--  1 willhill willhill  62K Jun 29 13:48 
debian-ch08s06-compiling_a_new_kernel.pdf
drwxr-xr-x 25 willhill willhill 4.0K Jun 29 15:40 linux-4.2.5
-rw-r--r--  1 willhill willhill 3.7K Jun 29 15:40 
linux-firmware-image-4.2.5-gnu1_4.2.5-gnu1-1_i386.deb
-rw-r--r--  1 willhill willhill 9.2M Jun 29 15:40 
linux-headers-4.2.5-gnu1_4.2.5-gnu1-1_i386.deb
-rw-r--r--  1 willhill willhill 1.1M Jun 29 15:40 
linux-libc-dev_4.2.5-gnu1-1_i386.deb
-rw-r--r--  1 willhill willhill  29M Jun 29 15:40 
linux-image-4.2.5-gnu1_4.2.5-gnu1-1_i386.deb

all packages installed without issue and archived for future use.  

The new kernel booted.  After starting cryptsys again, I was able to mount the 
10TB drive as dm-3 to /mnt.

This method does not cleanly unmount devices, so it's only useful for drives 
you want on till shutdown.  Gnome-disks in Debian Stretch does clean mounts 
and unmounts, so I can sync things on other computers running that software 
until I understand how it works.  I managed to install a newer version of 
gnome-disks on Debian Wheezy through the Guix package manager, but it was 
unable to mount or even see drive volumes.  

This method might also completely blow up your files because, I don't think 
that I installed newer versions of e2fsprogs.  I imagined that I might find 
and install those through Debian backports, but I did not document it and two 
months later don't remember if I did or not.  I'm not too worried about the 
files on my TV computer blowing up.  

Happy hacking.