[coreboot] Now Proposal for cross-compiler Re: Simnow & payloads (Was: something else)

Marc Karasek Marc.Karasek at Sun.COM
Wed May 14 23:31:49 CEST 2008


I agree with you about it being more of a coreboot problem than a 
toolchain problem. (Although, building a cross-compiler is really quite 
simple, if you use the crosstools scripts. It is just a matter of 
running a script.) I will put together all of my information on what is 
broken and what errors I am seeing as soon as I can.

I know that (recently) gcc/binutils has been through a "tightening" 
process where they have been trying to cleanup their act, by following 
more strict compiling/linking. This has resulted in quite a few builds 
being broken due to things that were once allowed and are not allowed now.

I like the idea of being able to "specify" a local toolchain. This would 
give someone the option to compile and build with a "known" good 
toolchain. I feel this is useful in that toolchain problems can be very 
difficult to track down. They normally manifest themselves in a seg 
fault when running the compiled application or a very ambiguous error 
message during linking/compiling. This would provide a path for someone 
to continue on with their development/testing while (potentialy) someone 
else looks at the build problem.

I will look at this and see what changes would need to be made to 
buildrom to make so you can specify a different local compiler. This 
would follow along the lines of $(CROSS-COMPILER) macro that is usually 
used for compiling an application with a cross-compiler.


Marc Karasek
Sun Microsystems
mailto:marc.karasek at sun.com

Jordan Crouse wrote:
> On 14/05/08 10:58 -0400, Marc Karasek wrote:
>> Jordan, Marc, Ron,  et all.
>> I found the problem with building coreboot-v2.  It was the binutils.  I 
>> believe the seg fault in linking tint/coreinfo is the same issue.  I will 
>> try to verify this soon.
>> I would like to propose that we move to a cross-compile type of 
>> environment.  We could use crosstools scripts to build a complete 
>> environment that would go under /opt/crosstools. This could then be used by 
>> buildrom to build with.  The advantage is that everyone will be on the same 
>> page in terms of gcc/binutils/glibc versions and we can have a better 
>> control over what tools
>> are used.  It gets us away from any distro/tools dependencies.  It will 
>> also let us test new toolchains in a very controlled environment.  Another 
>> added bonus with a common set of tools is that third-party developers
>> can use this without worrying about toolchain issues.
>> I have some experience in using cross-compilers from other embedded 
>> projects.  I have already setup crosstools with gcc 4.1.0 / binutils 2.16 / 
>> glibc 2.3.6 on my system.  I could take on the task of modifying buildrom 
>> to use this toolchain instead of the "native" toolchain.   I
> I feel very strongly that this should not be mandatory.  I appreciate
> the trouble you have had, but I think that adding a mandatory cross-compile
> toolchain is too high a barrier for entry for novice buildrom users.
> I have always believed, and I will always believe that the reason that 
> any given toolchain doesn't work out of the box is the fault of the software
> you are compiling and not the fault of the toolchain.  The moment we start
> to turn a blind eye to our own faults and start blaming toolchains, then we
> have started down a slippery slope.  Eventually, coreboot and buildrom and
> the payloads will only be compilable with a special toolchain that is six
> years old and we'll be content to sit around and blame it all on the compiler
> team.  Thats not a future I relish.
> If libpayload based payloads are not building, then I consider that a
> personal failure, and we need to resolve it.  Please send me the details.
> That all said, I would be perfectly happy to let the user specify a 
> local toolchain to compile buildrom, as long as that behavior is configurable
> and the default remains to use the system toolchain.  I'm sure that your
> experience with crosstools will be good for a wiki page describing the 
> care and feeding of a cross-compile toolchain and how to use it with
> buildrom.  I look forward to seeing that.
> But I beg you, please give us as much information as you have about your
> failures so that we can try to fix them in the code.  And everybody else,
> we need to stop throwing our hands up when we encounter toolchain issues -
> we need to understand them and why there is a much better then average
> chance that it is our code that is to blame.
> Thanks,
> Jordan

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