GDB Testing, ChangeLogs, and Expanding Vagrant

July 17, 2018

This is a follow up on “Building GDB From Source”, and uses the vagrant environment described in the previous post. It covers doing a bunch of basic things, which are largely independent of each other.

Generating a Patch:

Patches are git diffs and can be generated:

From the last commit: git format-patch -1 HEAD
From unstaged changes git diff > changes.patch

Generating a ChangeLog:

Use the mklog command from the GDB wiki.

1) Download the file or run

wget -O mklog https://gcc.gnu.org/viewcvs/gcc/trunk/contrib/mklog?view=co

2) Give executable priviledges

chmod +x mklog

3) Run on the PATCH file:

./mklog changes.patch > ChangeLog

4) Explain the ChangeLog

emacs ChangeLog

Testing a Patch:

This part is based off of the “Working on GDB” approach from gbenson.net.

Find the latest branch here, i.e. gdb-8.2-branch and then check it out (or just use HEAD):

git checkout gdb-8.2-branch

1) Build and then run the testsuite without any changes:

mkdir 8.2 && cd 8.2
../configure --enable-targets=all --with-expat
make
make check -j4 >& ../8.2.log
cd ..

2) Build and then run the testsuite with the patch:

git apply changes.patch
mkdir 8.2-changes && cd 8.2-changes
../configure --enable-targets=all --with-expat
make
make check -j4 >& ../8.2-changes.log
cd ..

3) Diff the file:

diff 8.2.log 8.2-changes.log

Exporting a Patch from Vagrant:

1) Run vagrant ssh-config and find the values Port and Identity File in the output.

2) Copy the desired file from vagrant to the host machine:

scp -P {Port} -i {IdentityFile} vagrant@127.0.0.1:~/gdb/changes.patch .

Expanding a Vagrant Box:

In order to accomodate the size of multiple GDB installations, the default Debian box needs to be made bigger, since it only has about 8GB of space. This involves two parts: expanding the size of the VirtualBox disk partition and expanding the file system.

1) Expanding the VirtualBox disk size:

First, convert the stretch.vmdk disk file to a stretch.vdi one and make it bigger and then covert it back. It will be located within the VirtualBox VMs folder. This approach is common [1] [2].

On Unix:

vagrant halt
cd ~/VirtualBox\ VMs/debian_default_*
VBoxManage clonehd stretch.vmdk stretch.vdi --format vdi
VBoxManage modifyhd stretch.vdi --resize 50000
rm -f *.vmdk
VBoxManage clonehd stretch.vdi stretch.vmdk --format vmdk
rm -f *.vdi

On Windows: (Replace USERNAME)

vagrant halt
cd "C:\Users\USERNAME\VirtualBox VMs\debian_default_*"
"C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" clonehd stretch.vmdk stretch.vdi --format vdi
"C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" modifyhd stretch.vdi --resize 50000
del *.vmdk
"C:\Program Files\Oracle\VirtualBox\VBoxManage.exe" clonehd stretch.vdi stretch.vmdk --format vmdk
del *.vdi

This resizes the disk size to 50GB. 20GB would also work (use --resize 20000).

Return to the vagrant directory. Then run:

vagrant up
vagrant ssh

2) Expand the primary partition size:

Check the file system:

df -h

This should show that /dev/sda1 has 8.7G capacity mounted on /. If there is a different disk instead, then use that one going forward.

Next print out the partitions:

sudo fdisk -l

There should be three: Linux, Extended, and Linux swap / Solaris.

Then run fdisk and the following commands (not the comments):

sudo fdisk /dev/sda
d           # Delete all partitions
1
d
2
w           # Write changes

Create a new primary partition:

sudo fdisk /dev/sda
n           # New partition
p           # Primary partition
1           # At /dev/sda1
<enter>     # Default start location (at 2048)
+45G        # Partition size
No          # Don't remove the ext4 signature
w           # Write changes

Create swap partition:

sudo fdisk /dev/sda
n           # New partition
e           # Extend partition
4           # At /dev/sda4
<enter>     # Default start location
<enter>     # Partition size maximum
w           # Write changes

Change partition type to swap:

sudo fdisk /dev/sda
t           # Chang Partition Type
4           # At /dev/sda4
82          # Linux swap / Solaris
w           # Write changes

Restart the vagrant box (Note that it may take a while this time with some error messages):

logout
vagrant halt
vagrant up
vagrant ssh

3) Resize the file system to take up the whole partition:

sudo resize2fs /dev/sda1

sudo mke2fs -t ext4 /dev/sda4
sudo tune2fs -U random /dev/sda4
y
sudo blkid

Finally copy the UUID of /dev/sda4 and write it in the file below, replacing the UUID under the # swap was on /dev/vda5 during installation comment (and change the comment):

emacs /etc/fstab

Then restart with:

logout
vagrant halt
vagrant up
vagrant ssh

And running: df -h should show the new expanded size.