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Re: Renesas SH4 support in emdebian



On 02/25/2010 11:16 PM, Nobuhiro Iwamatsu wrote:
Hi,

2010/2/16 Hector Oron <hector.oron@gmail.com>:
  

Those are good news. I think, correct me if I am wrong, cross compiler
you have built it is a bare metal compiler. In case you need a
compiler linked against eglibc, you can try to do it the way it is
explained at:

 http://wiki.debian.org/EmdebianToolchain#Buildyourownfromsources

A long time ago I tested it, it was working fine for me, I can't
remember if by that time sh* architectures were in dpkg tables or I
had to add them locally.

I am short of time to work on this, but let me know if you have any
issues or if I can help either way.

    
I noticed it being slightly different from how to make of my cross compiler.
I intend to rebuild  toolchain.

Thank you.

Best regards,
  Nobuhiro

  

I was originally going to write this e-mail to Nobuhiro directly, but since this discussion was started here on the Emdebian list I thought I would start with an open letter in case some of the answers are of interest to the wider Emdebian audience.  Please let me know if and when I should take this discussion off list, I don't want to cause undo chatter.

I am currently evaluating SH as a potential architecture for a project.  I would like to target a baked Emdebian as the distribution for this project.  This would be my first attempt at doing a full Emdebian distro, and normally I would rather start with a known entity like armel, but the processor choice may be dictated by other issues.  I've read and re-read this thread a few times, as well as much of Emdebian list traffic over several recent months, and I have some questions.  >From my understanding,

1. The Emdebian toolchain for SH can be built (in fact I have just built the gcc-4.4 cross-compiler myself in Squeeze using this method http://wiki.debian.org/EmdebianToolchain#Buildyourownfromsources).  There is some mention, however, in the notes on the Renesas site (https://oss.renesas.com/modules/document/?Debian%20%2F%20SH4) that the SH Debian distribution is being built with a special patch that makes it binary incompatible with cross compilers.
"We have applied a patch concerning the _fpcr_value to eglic in Debian/SH4 distribution. Note that eglic of Debian/SH4 is not compatible with binary packages that were built with a cross compiler, eglibc, or glibc included in other Debian distributions."
Would this mean that code compiled with an Emdebian built cross compiler will be incompatible with packages that are available in the Debian ports mirror, and/or also those that have been built on the Emdebian grip server?

2. I realize from reading the thread that there is no testing or testing migration support for SH, since it is still a Debian "port" architecture and not yet on the official Debian server.  I'm also trying to understand the issues with reprepro and the other tools used to work with Emdebian.  I also understand that this is very unlikely to be rectified for SH in the Squeeze time-frame.  Does this then mean that if one were going to try to release a system based on SH and Squeeze, that it would only work if one were to create their own private Grip mirror for SH at some given point so that they could cut off the of updates to the packages at about the time that Squeeze is released?  In other words, will the fact that the ports mirror only supports unstable mean that it will continue to process updates for a Squeeze distribution beyond Squeeze's freeze?

Am I correct in assuming that this method would also make it very hard to pickup any updates whatsoever, since it would be very hard to manually feed those updates to reprepro?  Sorry I have tried reprepro in the past, but I am nothing of an expert in its nuanced use.  I do remember it was hard to get certain manual operations to occur smoothly (at least in the Etch era when I last used it).

One other thought that occurred to me is that I could use reprepro to pull a private source only repository of just the packages I want in my distribution based on Squeeze testing (and eventually stable) and then setup my own private autobuilder network to build those packages.  Does autobuilder only support native building, or is there a way to setup to use an Emdebian cross compiler environment to build packages?

Thanks in advance for any help,

-Jim Heck



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