[ELDK] Just starting - ipkg errors

[Larry Baker]

On 6 Aug 2013, at 1:34 AM, Wolfgang Denk wrote:

> Maybe the FAQ was not explicit enough about the assumptions it was
> based on.  Please re-read it now.  I added the following explanation:
> 
> 	Note: All tools working with software packages have to
> 	maintain a certain "package database". This may be a real
> 	database (like Berkeley DB files as used by the rpm tool), or
> 	a plain text file (like used by the ipkg tool). The important
> 	message is: without such package database, you will not be
> 	able to work with packages, like adding new, or listing,
> 	removing or updating already installed ones.
> 
> 	The following operations will therefore only be possible on
> 	file system images that contain such package information. Note
> 	that most of the "small" root file system images in ELDK (say,
> 	core-image-minimal or core-image-basic) do not contain any
> 	package database.
> 
> Hope this helps to avoid future confusions.

Yes, that is very helpful now.

> This is impossible.  With the ready-to-use file system images, you can
> use packing tools only if the required package information is included
> with the image.  You cannot operate on any information that is not
> present at all.
> 

> It does not only not contain a package manager, it also does not
> contain any packaga database information.

Is this package database removed by some step in the Yocto rootfs build?
Even though a target does not have a package manager installed, it seems
to me to be quite useful to have the package database (as long as it is not
large).  If this is under the control of DENX, may I suggest this be considered
a request item for a future ELDK release?

> The best way to do this is to build a new file system image customized
> to your requirements.  that means starting from the source, creating
> your own biuld target (by copying one of the existing ones - here say
> core-image-basic.bb and modifying it according to your needs), and

I did not find any .bb files in the Qt SDK that I installed with the basic rootfs.
(Not because I plan to use it -- I am building a console-only system.  I just
wanted to be sure I saw everything in a development SDK that you provide.)
I assume I will find the .bb files you used and your Yocto build scripts in the
git repository so that I can learn from them and modify them for my purposes?

FYI: The links on http://www.denx.de/wiki/view/DULG/ELDKAvailability to
http://ftp.denx.de/pub/eldk/ and http://mira.sunsite.utk.edu/eldk/ and are no
good.  And, most of the HTTP reachable sites are pretty stale.

> then building it.  You may find HOB [1], a graphical user interface
> for BitBake, to be helpful, at least for the first steps.
> 

> [1] https://www.yoctoproject.org/documentation/hob-manual
> 
> Actually ELDK inherits all these things from the Yocto Project, so
> this is more talking about Yocto ways than ELDK ways.  Note that I'm
> using the plural form here, as there is not a single, prescribed way
> that everybody has to use; instead, Yocto / ELDK offers you the
> freedom to chose whichever tools you consider useful for your target
> configuration.  The provided root file system images are intended to
> allow you  quick start, to have your system running with some
> predefined configurations very quickly.  But these are just examples,
> which you can copy, or modify, when designing your own target root
> file system.

If I am able to find the recipe you use to build the basic rootfs for armv5te,
I will first try to replicate your steps.  I am hoping to only have to slightly
modify what you have already done to suit my purposes.  I prefer, if possible,
to use your repository and example root file systems.

> Or copy it from your host system.

Yes, that was my plan.

> Not quite.  A machine configuration describes the hardware you are
> running on, i. e. for example the processor architecture etc., but
> this is completely independent from the actual content of any root
> file system image you may generate.  It will most probably make sense
> that you define a custome machine matching your own hardware,

I am familiar with the change to use device trees now for ARM kernels.
Luckily, the board I use is supported using the stock Linux kernel and
description files for one of the development boards supported by the
SoC manufacturer.  I do not have to worry about that.  (Good thing for
me -- I am a systems programmer, not a hardware developer.)
 
> but you
> will _also_ have to define your own root file system image - these are
> two separate tasks.

Yes, this is my focus.

> Note however that you are entering a very complex set of topics here.
> This is not a failure of Yocto, but the comlexity is inherent to the
> class of problems we have to solve here (all other build systems are
> similar complex).  You have been warned. Here Abide Monsters And
> Dragons.

And, so much adventure awaits us!

Thank you again,

Larry Baker
US Geological Survey
650-329-5608
baker at usgs.gov