Re: [PATCH] imd: model and compatible missing in metadata

["Scherer, Thorsten" <thorsten.scherer@eckelmann.de>]

Hello,

On Tue, Jan 22, 2019 at 09:53:37AM +0100, Uwe Kleine-König wrote:
> Hello,
> 
> On Tue, Jan 22, 2019 at 09:10:40AM +0100, Scherer, Thorsten wrote:
> > i spent some time trying to understand the usage of imd_used etc. 
> > 
> > In another reply I stated:
> > 
> > 'I misread the documenation on IMD as "of_compatible and model will be
> > figured out and put into the proper location by barebox".'
> 
> That is wrong. The current code doesn't ensure that and I don't see a
> way how this could be done comfortably without per-board changes.
>  
> > I am not so sure, if that is really the case.
> > 
> > As far as i understand things:
> > 
> > 1. 	of_compatible and model are (should be) automagically added to imd from the
> > 	entries in the dts.
> > 
> > git show 97e81f2d7 | grep -A 1 'For.*model.*of_compatible'
> > cat scripts/gen-dtb-s | grep -A 23 -B 3 'barebox_imd_0'
> 
> The imd tags for compatible and model are generated, but not
> automatically included with this change. This is AFAICT the current
> state.
> 
> The problem is that the needed information is included in the "barebox"
> image (i.e. the file with the name "barebox" that is build in the top
> build dir) but then there is an additional step that extracts "all
> needed" parts from that image to create a binary that then is able to be
> started on your target. So if "barebox" has three entry points for
> different machines, there are three images generated and each only has a
> single entry point. Unused functions and data structures are stripped.
> The linker detects that the imd section that contains the compatible and
> model is not used and so this goes away in all three generated binaries.
> 

Thank you for the explanation.  Now things start to clear up a bit.  

> > 2.	the IMD_USED macro puts arbitrary tags in the metadata.  Which may
> > 	also be a tag named model.
> 
> The IMD_USED claims a certain data structure is used such that the
> linker doesn't throw it away.
>  

Ok.

> > Now I wonder, if the lack of the patch just covers up an issue at another
> > place or if there is something (in the context of multi image support?) which
> > I do not understand. 
> 
> Did you look at the patch I sent you?
> 

I did.  But not closely enough.  On the invokation of imd, model and
of_compatible were not displayed.  Somehow I did not get, that your
patch was made to apply for the imx25 boards and not for the imx6
board (the one which I was checking).  After adjusting the lowlevel.c
file of the imx6 board, everything went fine.

> > Maybe there is something messed up with the entries in
> > the device tree?
> > 
> > https://www.spinics.net/lists/arm-kernel/msg699453.html
> 
> This is unrelated, this is a patch for Linux to add a device tree.

Right.  It didn't make sense to add this.

> 
> Best regards
> Uwe
> 

Again, thank you for feedback.

Best regards
Thorsten

> -- 
> Pengutronix e.K.                           | Uwe Kleine-König            |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |

-- 
Mit freundlichen Grüßen
Thorsten K. Scherer
Diplom-Ingenieur (FH)
Kälte- und Gebäudeleittechnik
Datentechnik


Eckelmann AG
Berliner Str. 161, 65205 Wiesbaden
Telefon +49 611 7103-329     
Fax +49 611 7103-133
thorsten.scherer@eckelmann.de
https://www.eckelmann.de

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