WEBVTT

00:00:02.000 --> 00:00:08.000
Hello everyone, welcome to my presentation.

00:00:08.000 --> 00:00:17.000
I will introduce GNU/Screen to Debian Installer today.

00:00:19.000 --> 00:00:24.000
I will show you its background.

00:00:24.000 --> 00:00:26.000
What is Debian Installer,

00:00:26.000 --> 00:00:30.000
What is GNU/Screen,

00:00:30.000 --> 00:00:35.000
Why I want GNU/Screen in Debian Installer

00:00:35.000 --> 00:00:40.000
and How to add GNU/Screen support in it.

00:00:42.000 --> 00:00:47.000
First, The background.

00:00:47.000 --> 00:00:51.000
I know that most of you know the Debian Installer.

00:00:51.000 --> 00:00:55.000
It is just an installer.

00:00:55.000 --> 00:01:01.000
But actually, It is a bootable Debian environment,

00:01:01.000 --> 00:01:07.000
which is minimized in size.

00:01:08.000 --> 00:01:15.000
That is to say, there is no document in the image.

00:01:15.000 --> 00:01:34.000
There is no other non-replicated usually-useful information for normal people, which is usually putted in "/usr/share/doc".

00:01:34.000 --> 00:01:37.000
But installer stage, we don't need them.

00:01:37.000 --> 00:01:44.000
So, It contributes for minimizing environment.

00:01:44.000 --> 00:01:50.000
Previously, we have a installer in one or two floppy disks.

00:01:50.000 --> 00:01:53.000
It means that installer was very small.

00:01:53.000 --> 00:01:55.000
Nowadays, it is not possible.

00:01:55.000 --> 00:02:04.000
Because the kernel size is already over size of the floppy.

00:02:04.000 --> 00:02:14.000
Second, there is a partitioner inside the installer.

00:02:14.000 --> 00:02:24.000
So, you can do the partition and create a new disk image inside the installer.

00:02:24.000 --> 00:02:36.000
After that, we can do the "debootstrap" to install Debian environment for you.

00:02:36.000 --> 00:02:41.000
Finaly, the installer will install boot loader.

00:02:41.000 --> 00:02:53.000
There is all kinds of boot loader, such as <b>GRUB</b> for <i>PC</i> or for <i>ARM64</i>.

00:02:53.000 --> 00:03:07.000
For <i>ARM</i> platform, such as <i>armel</i> or <i>armhf</i>, we use <b>flash-kernel</b> as a boot loader.

00:03:12.000 --> 00:03:15.000
What is GNU/Screen?

00:03:15.000 --> 00:03:17.000
First, It is a terminal multiplexer.

00:03:17.000 --> 00:03:28.000
It means that you can have multiple virtual terminal in real terminal.

00:03:28.000 --> 00:03:42.000
And you can switch one virtual terminal to another virtual terminal by a shortcut.

00:03:42.000 --> 00:03:47.000
In GNU/Screen, the shortcut is "Ctrl-A + 1", 2, 3, 4.

00:03:47.000 --> 00:04:00.000
And Tmux (GNU/Screen alternatives)
use "Ctrl-B + 1", 2, 3, 4.

00:04:00.000 --> 00:04:14.000
Then you must be thinking why we need GNU/Screen in Debian Installer.

00:04:14.000 --> 00:04:19.000
What is the benefit?

00:04:19.000 --> 00:04:22.000
Let me show you normal installer.

00:04:22.000 --> 00:04:28.000
This is a normal installer.

00:04:28.000 --> 00:04:30.000
We have UI.

00:04:30.000 --> 00:04:42.000
And if we face some problem, such as partitioning or creating new disk image, we want to check the log.

00:04:42.000 --> 00:04:49.000
We can press the key "Alt-F4"
to switch to the log console.

00:04:49.000 --> 00:04:55.000
This is a case for normal PC.

00:04:55.000 --> 00:05:03.000
If you want to switch back,
we can press the "Alt-F1".

00:05:03.000 --> 00:05:06.000
I can show you the demo.

00:05:53.000 --> 00:05:56.000
This is a normal Debian Installer screen.

00:05:56.000 --> 00:06:00.000
I can enter "Alt-F2".

00:06:00.000 --> 00:06:06.000
Command line appears.

00:06:06.000 --> 00:06:09.000
I can see lots of stuff here.

00:06:09.000 --> 00:06:17.000
By "Alt-F4", you can see the logs here.

00:06:19.000 --> 00:06:22.000
If we want to turn back,
we can enter "Alt-F1".

00:06:22.000 --> 00:06:26.000
Then we go back.

00:06:26.000 --> 00:06:28.000
This is a case for normal PC.

00:06:28.000 --> 00:06:36.000
But, there is no such convenient methods
in embedded.

00:06:55.000 --> 00:06:58.720
For embedded device
such as <i>armel</i> or <i>armhf</i>

00:06:58.720 --> 00:07:09.000
we usually install using the serial console
or the SSH over the network.

00:07:09.000 --> 00:07:14.000
So, there is the only one real screen
for you.

00:07:14.000 --> 00:07:17.150
There is no other screen.

00:07:17.150 --> 00:07:19.000
Actually, there is a way.

00:07:19.000 --> 00:07:21.000
You can see the previous page.

00:07:21.000 --> 00:07:29.000
There is a "Go Back" option here.

00:07:29.000 --> 00:07:34.000
We can go back and we can have this menu.

00:07:34.000 --> 00:07:42.000
This is an advanced menu and you can enter a shell from here for embedded device.

00:07:42.000 --> 00:07:46.000
After you enter a shell,
you can check the logs.

00:07:46.000 --> 00:07:52.000
The log is in "/var/log/syslog".

00:07:52.000 --> 00:07:54.000
It is there, you can check it.

00:07:54.000 --> 00:07:58.000
But, if you want to do it,

00:07:58.000 --> 00:08:03.000
every time you have to go back
and enter the shell.

00:08:03.000 --> 00:08:05.000
You cannot do it all the time either.

00:08:05.000 --> 00:08:10.000
Because sometimes the installer is running to install packages.

00:08:10.000 --> 00:08:16.000
You cannot do it at anytime
like in a normal PC.

00:08:16.000 --> 00:08:18.000
I was just thinking,

00:08:18.000 --> 00:08:24.000
if we have GNU/Screen introduced
into the Debian Installer,

00:08:24.000 --> 00:08:36.000
we can have it simple and convenient as a normal PC in the embedded area like <i>armel</i>.

00:08:42.000 --> 00:08:47.000
So, I have started to work for it.

00:08:50.000 --> 00:08:54.000
So, How to achieve it?

00:08:54.000 --> 00:08:58.000
After some search, I found that

00:08:58.000 --> 00:09:07.000
I need to support GNU/Screen binary package and its dependencies such as library to support udeb.

00:09:07.000 --> 00:09:18.000
udeb is special format for Debian Installer
which minimize installer image.

00:09:18.000 --> 00:09:22.000
That is to say,
it remove documents for example.

00:09:22.000 --> 00:09:32.000
So, we have to support udeb
for GNU/Screen and its library.

00:09:33.000 --> 00:09:40.000
And, we need to add those udebs
into the Debian Installer image.

00:09:42.000 --> 00:09:52.000
The third one is that we need to write some script to start GNU/Screen in Debian Installer.

00:09:55.000 --> 00:10:00.000
First, udeb support.

00:10:05.000 --> 00:10:13.000
Normally, udeb is controlled by "debian/control".

00:10:15.000 --> 00:10:19.000
it is like every binary packages
for the source packages.

00:10:19.000 --> 00:10:28.000
So we just add additional section
for supporting a udeb (new binary).

00:10:28.000 --> 00:10:38.000
After that, we just create a new "-udeb.install" file.

00:10:38.000 --> 00:10:49.000
And it is almost identical to the original ".install" file, but entries for unnecessary file are removed.

00:10:49.000 --> 00:10:53.000
After that we can create a patch.

00:10:53.000 --> 00:11:05.000
Then submit it to package maintainer
to let him or her to incorporate my changes.

00:11:05.000 --> 00:11:12.000
We add the new udeb package.

00:11:12.000 --> 00:11:15.000
But, if the package is maintained by DM,

00:11:15.000 --> 00:11:28.000
unfortunately DM need to ask DD
to sponsor the package to upload.

00:11:28.000 --> 00:11:35.000
For the same reason, the package will stay
in NEW queue in ftp-master.

00:11:35.000 --> 00:11:40.000
And we need to wait the ftp-master
to approve the upload.

00:11:40.000 --> 00:11:49.000
So, it takes much longer time
than normal packages.

00:11:52.000 --> 00:12:01.000
What I do is to add these udeb support
of GNU/Screen and it's dependencies.

00:12:01.000 --> 00:12:10.000
I created four Bug reports,
actually these are four bugs with patches.

00:12:28.000 --> 00:12:34.000
After that, we can have udeb package
that are ready to use.

00:12:34.000 --> 00:12:40.000
But, we still need to include
in the Debian Installer image.

00:12:40.000 --> 00:12:54.000
So, I patched to "debian-installer.git" repository
to support it.

00:12:56.000 --> 00:13:08.000
And finally we need to start GNU/Screen command
after we started Debian Installer.

00:13:08.000 --> 00:13:22.000
We also need GNU/Screen configuration to emulate Debian Installer environment like PC.

00:13:22.000 --> 00:13:29.000
We actually have four virtual screen
in the Debian Installer.

00:13:29.000 --> 00:13:37.000
First one is main screen, second is command
line console, and last is log console.

00:13:37.000 --> 00:13:42.000
We want to emulate them.

00:13:49.000 --> 00:13:54.000
I want to show you the demo.

00:14:01.000 --> 00:14:06.000
Actually, I run the Debian Installer
on virtual machine.

00:14:29.000 --> 00:14:34.000
This is the Debian Installer
with GNU/Screen support.

00:14:34.000 --> 00:14:40.000
So, we have four virtual terminals here,
1, 2, 3, 4.

00:14:40.000 --> 00:14:56.000
And I can switch terminal by a shortcut
such as "Ctrl-A + 2", "Ctrl-A + 3", and "Ctrl-A + 4".

00:14:56.000 --> 00:15:01.000
It is a log.

00:15:06.000 --> 00:15:12.000
As a PC side, as you see now,
it seems not much useful.

00:15:12.000 --> 00:15:17.000
Because we can use "Alt-F1", "Alt-F2",
and "Alt-F3" to switch.

00:15:17.000 --> 00:15:23.000
But for embedded side, It is much useful.

00:15:35.000 --> 00:15:40.000
I have a progress update.

00:15:40.000 --> 00:15:47.000
Actually these action items
are already done.

00:15:47.000 --> 00:15:53.000
For example, first two packages are for library.

00:15:53.000 --> 00:15:56.000
Actually, it was not needed at all.

00:15:56.000 --> 00:16:05.000
Because, I learned that from Mr. Laurent,

00:16:05.000 --> 00:16:09.000
GNU/Screen can be configured
to compile twice.

00:16:09.000 --> 00:16:24.000
First time is for normal GNU/Screen and second time is for the one which does not use <i>audit</i> and <i>pam</i> library.

00:16:24.000 --> 00:16:32.000
So, it can make GNU/Screen udeb binary minimized.

00:16:32.000 --> 00:16:38.000
Actually, library which needs
to be really supported is <i>ncurses</i>.

00:16:38.000 --> 00:16:49.000
<i>ncurses</i> has been uploaded to the ftp-master two weeks ago with the GNU/Screen binary package.

00:16:49.000 --> 00:17:06.000
For Debian Installer image, I just pushed a commit after Debian Installer Stretch Alpha 7 was released this week.

00:17:06.000 --> 00:17:10.000
Since I just pushed the commit
after the release,

00:17:10.000 --> 00:17:21.000
you can now try GNU/Screen
in Debian Installer daily image.

00:17:29.000 --> 00:17:32.000
Which device will benefit from it?

00:17:32.000 --> 00:17:43.000
These are usual some ARM boards installed
by serial console or SSH network console

00:17:43.000 --> 00:17:56.000
and some big machines
like SPARC64 or IBM s390/s390x.

00:17:56.000 --> 00:18:01.000
Even some PC can benefit from it.

00:18:01.000 --> 00:18:04.000
Because some PC are headless.

00:18:04.000 --> 00:18:13.000
There is no HDMI or VGA ports
on that kinds of PC-server-like PC.

00:18:17.000 --> 00:18:26.000
I would like to thank various people through early request-for-comment stage on my proposal

00:18:26.000 --> 00:18:35.000
and the help during
my udeb package upload stage.

00:18:35.000 --> 00:18:37.000
Thank you very much.

00:18:37.000 --> 00:18:42.000
[Applause]

00:18:42.000 --> 00:19:02.000
Are there any questions?

00:19:02.000 --> 00:19:04.000
[chair]: OK, do it.

00:19:04.000 --> 00:19:13.000
[questioner 00]: First of all, I use a SPARC embedded systems all the time.

00:19:13.000 --> 00:19:15.000
[questioner 00]: So, absolutely this will be a great help.

00:19:15.000 --> 00:19:19.000
[questioner 00]: Thank you very much for all your work.

00:19:19.000 --> 00:19:21.000
[questioner 00]: I really appreciate this.

00:19:25.000 --> 00:19:32.000
[question 00-00]: What was the one
thing that you found hardest with doing this?

00:19:32.000 --> 00:19:39.000
[question 00-01]: What did make you surprised the most "How easy it was"?

00:19:39.000 --> 00:19:44.000
Actually, most difficult part
is uploading the package.

00:19:44.000 --> 00:19:50.000
Because one package is maintained by DM.

00:19:50.000 --> 00:19:58.000
Usually DM can upload
without DD sponsorship.

00:19:58.000 --> 00:20:01.000
But, since udeb is regarded as new package,

00:20:01.000 --> 00:20:06.000
we need a DD to sponsor it.

00:20:06.000 --> 00:20:19.000
I think it takes almost two month through the process.

00:20:21.000 --> 00:20:24.000
[questioner 00]: And one thing you found very easy to do,

00:20:24.000 --> 00:20:26.000
[questioner 00]: which you thought got to be hard?

00:20:26.000 --> 00:20:29.000
mmm...

00:20:29.000 --> 00:20:30.000
[questioner 00]: Nothing is not all hard?

00:20:30.000 --> 00:20:31.000
[laughs]

00:20:31.000 --> 00:20:34.000
From technical side, it was not hard.

00:20:34.000 --> 00:20:37.000
Because everything is there.

00:20:37.000 --> 00:20:42.000
I just write some simple patch
to add udeb support

00:20:42.000 --> 00:20:48.000
and some script to start
GNU/Screen in Debian Installer.

00:20:48.000 --> 00:20:52.000
So, from technical side, it is not so difficult.

00:20:52.000 --> 00:20:54.000
[questioner 00]: Awesome.

00:20:54.000 --> 00:20:55.000
Thank you.

00:20:55.000 --> 00:21:00.000
[questioner 00]: Next question?

00:21:01.000 --> 00:21:07.000
[questioner 01]: You said that it was already in Stretch Alpha 7...

00:21:07.000 --> 00:21:13.000
No, I pushed my commit after Stretch Alpha 7.

00:21:13.000 --> 00:21:15.000
[questioner 01]: OK, So is it gonna be after the freeze?

00:21:15.000 --> 00:21:16.000
Yes.

00:21:16.000 --> 00:21:17.000
[questioner 01]: OK.

00:21:17.000 --> 00:21:25.000
[question 01-00]: Do you know if adding all these components related to GNU/Screen, how much the size of image will be increased in?

00:21:25.000 --> 00:21:29.000
[questioner 01]: A lot or not much? Does it make any difference?

00:21:29.000 --> 00:21:41.000
Yes, Debian Installer image size will be little bit larger than before.

00:21:41.000 --> 00:21:49.000
For example, there are "QNAP" series which is armel architecture machine.

00:21:49.000 --> 00:21:57.000
"QNAP" series are supported by Debian Installer.

00:21:57.000 --> 00:22:00.000
But, "QNAP" series has size limitation.

00:22:00.000 --> 00:22:07.000
Because we put the kernel and initrd image
in flash memory

00:22:07.000 --> 00:22:16.000
and the flash memory size is about 2 MB for kernel and 4 MB for initrd.

00:22:18.390 --> 00:22:21.100
So, the size is limited.

00:22:21.100 --> 00:22:29.000
Whereas, the size of GNU/Screen udeb
package is about 500 KB.

00:22:29.000 --> 00:22:38.000
So, it might be impossible incorporate with this new feature into that specific images.

00:22:38.000 --> 00:22:43.000
For other images, I think it is OK.

00:22:43.000 --> 00:22:48.000
There is no big size limitation concerned.

00:22:57.000 --> 00:23:03.000
Currently, it is in Debian Installer daily build image.

00:23:03.000 --> 00:23:08.000
So, you can just try it in daily build image.

00:23:08.000 --> 00:23:22.000
And, URL is "https://d-i.debian.org/daily-images/".

00:23:22.000 --> 00:23:25.000
There are many images in there.

00:23:25.000 --> 00:23:41.000
Because there are images for all supported architectures such as amd64 and GNU Hurd etc.

00:23:42.000 --> 00:23:49.000
So, you need to choose the right architecture and image.

00:23:54.000 --> 00:23:56.000
This is my talk. Thank you very much.

00:23:56.000 --> 00:24:00.000
[Applause]