Cross platform building best practices (building 6 on 7)

[Alexander Sack]

On Fri, Jun 20, 2008 at 5:14 PM, Julian Elischer <julian at elischer.org> wrote:
> Alexander Sack wrote:
>>
>> On Thu, Jun 19, 2008 at 11:22 AM, Garrett Cooper <yanefbsd at gmail.com>
>> wrote:
>>>
>>> On Thu, Jun 19, 2008 at 6:29 AM, Alexander Sack <pisymbol at gmail.com>
>>> wrote:
>>>>
>>>> Hello Folks:
>>>>
>>>> I've done a lot of Googling and scouring the lists about this
>>>> particular subject so I apologize for rehashing it.  However, I'm
>>>> still confused on what's the best way to perform BSD cross platform
>>>> builds.  Ideally what I want to have is an environment whereby I can
>>>> build a 6.1-RELEASE tree on a 7.0-RELEASE box.  I thought originally I
>>>> could check out a 6.1 release version, perform make world, and then
>>>> use the output of that build as either a basis for a jail or a
>>>> toolchain.  However, as noted by previous threads, 6.x doesn't build
>>>> on a 7.x due to gcc4/binutils compatibility issues (please correct me
>>>> if I'm wrong).  I then thought I could potentially download a patched
>>>> binutils, copy it into src/contrib/binutils and that would potentially
>>>> fix it.  No dice (and I'm still debugging why since this binutils
>>>> package DOES build outside of the make world infrastructure without
>>>> issue, this very well could be pilot error on my part since I didn't
>>>> update the VERSION string and didn't trim the source files as per the
>>>> FreeBSD-deleteList etc.).
>>>>
>>>> I THEN thought if I build/install a gcc-3.x/bintuils toolchain I could
>>>> complie a 6.x on a 7.x machine.  Well I haven't done that yet since at
>>>> this point I believe I'm diverged from the path of FreeBSD build
>>>> enlightenment!  Moreover, if would be NICE if I could bootstrap the
>>>> normal dev tools from the exiting make world build tree.  I'm not yet
>>>> ready for a lot of hackery on the build tree without asking around.
>>>> :D!
>>>>
>>>> Does anyone due cross-platform builds (without host virtualization)?
>>>>
>>>> Thanks!
>>>>
>>>> -aps
>>>
>>> (I'll stick to just hackers@ because I don't want to pollute
>>> questions@ unnecessarily)
>>
>> Sorry I felt really bad actually cc'ing questions its just that my
>> last groking produced many threads in freebsd-questions as opposed to
>> hackers.  I'll try to be more attentive to my posts (I have a habit
>> cc'ing multiple forums because sometimes they apply but questions is
>> for normal troubleshooting, not cross-platform build issues!).
>>
>>> You touched on an important point. There were some code quality issues
>>> (I think) with 6.x that were resolved moving to 7.x, which caused
>>> gcc-4.2.x to barf.
>>
>> Probably but I'm not trying to point fingers!  :D!
>>
>>> gcc-4.2.x requires a newer version of binutils, just because (for API
>>> / usage compatibility).
>>
>> Yea understood.  To be honest, this isn't documented very readily.  I
>> first thought it was pilot error on me, then I decided to take a look
>> at what failed to compile (I believe it was an innocent extern).  And
>> then got lost in gcc/binutils hell.  Luckily I've smelled this problem
>> before and after some research confirmed by suspicion.
>>
>>> What you should probably do is create a jail then do your development
>>> for 6.x in a jail, 7.x in another, and (if you're bold enough ;)...)
>>> do 8.x development in yet a third. Jail's are a much better way to
>>> isolate things such that you don't have to worry about toolchain
>>> issues like these and are able to setup a sourcebase as the devs
>>> intended it (for the most part; you may run into issues with sysctls
>>> and virtual kernel stuff like that, but cest la vie... there isn't a
>>> better way I know of than that outside of running a VM).
>>
>> I figured you were going ot say that Garrett.  Well OK, but I still
>> need to bootstrap my dev environment for 6.x development on 7.x.
>> Since binutils compatibility makes my 6.x make world barf on 7.x,
>> where should I go?  I HAVE not parsed through a lot of the build
>> infrastructure yet but it would seem to be IF make world bootstraps
>> the world including the development tools, why can't I update
>> binutils/gcc inplace and then compile (or is this a regression issue
>> which I failed to grasp).  Or do I need to update binutils on my
>> *host* system itself?  i.e. what I'm really asking is does make world
>> bootstrap the right bintuils/gcc etc. and then use THAT to compile the
>> rest or does it just perform a host build of everything and plops it
>> in DESTDIR?
>>
>> Hope I make some sense here (still a n00b)....
>
> One thing we always strive for in FreeBSD is an upgrade path.
>
> As a general rule, a newer system should be able to run a jail
> populated with an earlier system. There are some small exceptions,
> for example you may need a new version of netstat, ps and libkvm
> in your jail. possibly grab them from the /rescue on the new system
> so they are statically linked.
> also 8.x systems will require that threaded programs from 6.x be dynamically
> linked so that they can be remapped to use libthr instead of libkse as
> libkse is not supported in 8.

So you are talking about binary/ABI compatibility yes?  So I would
assume what you are saying is I can take a 6.x system, create a
filesystem tarball, drop it on a 7.x system and then create a jail out
of it.

> asside from those I think that just about every thing else should be fine..
> I've run a FreeBSD 1.1 chroot on a freeBSD 7 system
> (I had to make 1 very small fix).
>
> At Ironport we build 4.x binaries on 6.x systems by spinning off
> a 4.x chroot as prart of the build process. (they need to link with 4.x
> third party binaries) so it's very esay to do.

I believe this answers my question but I want to confirm.  I THOUGHT
about this but I wanted a more *cleanroom* approach.  That's all.

-aps