[Sugar-devel] Hello, was Re: Hack to get a USB/SD to autologin to only "Sugar-desktop on a stick". from a F12-alpha live CD

[Douglas McClendon]

Hello,

My name is Douglas McClendon, and I created the ZyX-LiveInstaller which appears
  on track to becoming part of SoaS.  I also can accept praise and blame for
the LiveUSB persistence feature I implemented for fedora a couple years back,
as well as that strange file osmin.img which appears, and is in fact used to
optimize installation speed (by ~25-50%) for Fedora LiveCD/USB installs.

This thread seems like a good place to introduce myself to the list.  I don't
intend to be too active as I have other projects eating up my time, but I have
been a supporter of OLPC and sugar since first hearing about them.  In fact the
user interace idea of having multiple applications open full screen in seperate
workspaces is something I've been including in my derived LiveCDs since 2001
when I used Mandrake-7.1 for a home-theatre purposed LiveCD, with fullscreen
xmms, mozilla, and rxvt all started by default in their own virtual desktops,
with desktop view changable via lirc remote control.

Anyway, I'm pretty excited that it looks like the next version of SoaS will be
the first mainstream usage of my rebootless liveos installation technique.  You
can read all about it at-

http://viros.org/rebootless

Below, I'll try to add my perspective to this thread, to clear up what I can-

Thomas C Gilliard wrote:
> If I had been on a USB (liveuser) with a livefs plus persistence like 
> the strawberry .iso and live-usbcreator (or sh script) creates,
> 
> I would never have been able to do all of these yum installs,removes and 
> upgrades.

Actually, you can.  The way that I implemented LiveUSB persistence for fedora
was to utilize a file on the USB fat filesystem to act as the overlay device
for a devicemapper snapshot device with the normal ext3/4 filesystem as the
read-only base.  Fedora also added to their LiveOS special cases for /tmp and
/var/cache/yum to live in tmpfs, specifically so that doing things like yum
installs would work more efficiently.

Unfortunately due to this LiveOS architecture, things are 'tricky' and _heavy_
use of yum and in fact anything that creates and deletes lots of files, will
quickly exhaust the read-write overlay image file.  Unfortunatley even faster
than you might intuitively think.

> 
> The resulting 4GB USB seems to be a HD install with a real file structure.

In fact, the filesystem that lives on a LiveUSB is has just as much 'real file
structure', it is just however hidden behind a few layers of indirection.
Specifically the file /LiveOS/squashfs.img is a squashfs filesystem which
contains a single file - /LiveOS/ext4fs.img.  This file is the full 'normal'
root filesystem that you see during a live boot.  It is a filesystem in a
sparse loopback mounted file (which is part of a loopback mounted compressed
filesystem).

Both the normal anaconda liveinst LiveOS installer, as well as my ZyX
Rebootless LiveOS Installer, merely copy this deeply buried but normal
filesystem to the target installation disk.  The difference with my installer
is that it is copied _while in use_, _including the readwrite overlay changes_,
to disk.  Resulting in an install that doesn't require a reboot at the end of
installation to start using the installed system.

> 
> Something in the F12 Anaconda installer seems to be converting the live 
> fs to a real file system on the USB.

All anaconda does is the python equivalent of

dd if=/dev/mapper/live-osimg-min of=/dev/new_root_partition.

The '-min' part involves a devicemapper trick to prevent the unnecessary
writing of a hundreds of megs of zeros.

> 
> The ability to use a Custom Sugar live CD( If we can make one) for 
> testing on a PC and then installing to USB (or HD) appears to be a new 
> and different creature.

I agree with the other responder.  This doesn't seem new, except insomuch as
soas-v1 did not include either the anaconda or my LiveOS installer.

> 
> Or it seems to be...

I hope that clears things up.  I know I probably confused you Tom when I sent
you that list of 8 different linux installation methods.  Believe me, it is all
very confusing, and I should spend some time writing a whitepaper on how much
of the above happens.

peace...

-dmc



> 
> Cordially;
> 
> Tom Gilliard
> 
> Note:
> 
> I have posted a compressed .img file of the KDE/Sugar USB on:
> 
> http://people.sugarlabs.org/Tgillard/SDF12kdeSUGAR4GB.img.tar.gz
> 
> This can be inflated and burned with dd command to a 4GB USB for testing
> 
> See the accompanying  .txt file for information
> 
> 
> 
> Martin Dengler wrote:
>> On Tue, Sep 08, 2009 at 04:17:52PM -0700, Thomas C Gilliard wrote:
>>
>>   
>>> But [SoaS] is on a USB/SD installed from the "install from the
>>> desktop" to a real file system.
>>>     
>>
>> Huh?
>>
>>   
>>> Tom Gilliard
>>>     
>>
>> Martin
>>   
>> ------------------------------------------------------------------------
>>
>> _______________________________________________
>> Sugar-devel mailing list
>> Sugar-devel at lists.sugarlabs.org
>> http://lists.sugarlabs.org/listinfo/sugar-devel
>>   
> 
> ------------------------------------------------------------------------
> 
> _______________________________________________
> Sugar-devel mailing list
> Sugar-devel at lists.sugarlabs.org
> http://lists.sugarlabs.org/listinfo/sugar-devel