2+ video cards should work as well in Ubuntu as Windows

[Harry Coin]

In a regression in recent years, Linux has failed to keep a feature well 
supported by its own earlier versions and all the various Windows OSen: 
to simulate one large display as well with two or three possibly 
dissimilar graphics cards as it does with one card with two or three or 
more outputs.  The cost of graphics cards with many outputs comes at a 
great price and performance hit over more cards with fewer outputs.  
This is becoming particularly pressing now that processors support 
on-die graphics adapters in addition to PCI express graphics slots 
supporting video adapters which almost never have the same architecture 
as the on-die graphics.


The arrival of pre-supposed support for compositing has ended the use of 
Xinerama, which at one time was the approach to this problem.


Many will be quick to note xrandr is 'the new way'.  For graphics cards 
hosting on the same card enough outputs for the entire system, it works  
(though I've yet to find a linux system on which dragging monitor icons 
when there are 3+ around the display configurator works).  The command 
line interface for xrandr is, well, its own entire body of obscure 
knowledge.  No real comparison to the simple Windows display dragging 
and sizing GUI.


As a work around, because try though I did for days of searching and 
attempting solutions to make it work all-Ubuntu: I'm forced to use a 
Windows front end which does a flawless job with two low/mid-market 
graphics cards acting as an X server to a headless Ubuntu back-end. It's 
ugly.  But without it no work happens.  All because Ubuntu can't manage 
more than one graphics card forming a large simulated single display as 
once it did.   Indeed there are vendor specific expensive workarounds: 
Nvidia's SLI + base Mosaic, Radeon / Quadro multi-headed 'whole 
paycheck' graphics cards, etc.  but Ubuntu shouldn't rely on such things 
when others do so well with what was installed-- over against Ubuntu 
upgrades that render a previously working system broken.


I urge whoever it is that sets goals in these matters to consider this.  
Thanks for reading!


Harry G Coin
Bettendorf, Iowa


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Re: How to build systemd

[J Fernyhough]

On 04/08/16 15:45, Alex Lyakas wrote:
> Greetings,
>  
> I have downloaded the systemd package for trusty
> (http://packages.ubuntu.com/source/trusty/systemd) with “apt-get source
> systemd”.
>  
> Which commands should I issue to build it? Specifically I need to build
> udev and its accompanying tools (like scsi_id).
>  

The easiest way (I've found) to build packages from source is with
`debuild`, e.g.:

$> apt-get source systemd
$> cd systemd-204
$systemd-204> debuild

This will probably complain about missing dependencies. You can go
through the list and install manually, use `apt-get build-dep systemd`,
or install `equivs` and use `mk-build-deps` (which is what I would do as
it's then easy to remove the deps afterwards), e.g.:

$> mk-build-deps systemd
$> sudo gdebi systemd-build-deps_204-5ubuntu20.19_all.deb

(`gdebi` will automatically install dependencies, `dpkg -i` will not.
`mk-build-deps` will also run without an argument from within a source
directory, the above command makes it explicit and means there's not a
deb file created in the source directory.)

So, putting this together:

$~> sudo apt-get install equivs
$~> apt-get source systemd
$~> mk-build-deps systemd
$~> sudo gdebi systemd-build-deps_204-5ubuntu20.19_all.deb
$~> cd systemd-204
$systemd-204> debuild
$systemd-204> cd ..
$~> ls
[newly created package files]
$~> sudo apt-get purge systemd-build-deps
$~> sudo apt-get autoremove --purge


Be aware that this build will depend on the packages currently installed
on your system. A better approach (which is also used by e.g. Launchpad)
is to build in a chroot, probably using pbuilder:

https://wiki.ubuntu.com/PbuilderHowto
https://www.debian.org/doc/manuals/maint-guide/build.en.html

Once you have this set up you only need to use `pdebuild` instead of
`debuild`:

$~> apt-get source systemd
$~> cd systemd-204
$systemd-204> sudo pdebuild
$systemd-204> ls /var/cache/pbuilder/result/
[newly created package files]

This should automatically install all necessary buildeps within the
chroot and produce the debs (and other package files) in
/var/cache/pbuilder/result by default. To specify a target location use
`pbuilder --buildresult /target/location` (see `man pdebuild`).


There's an awful lot of documentation on the web to wade through for
package maintenance, and quite a bit is contradictory (or at least
inconsistent), but this should at least get you started.

J



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