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On Sunday 31 Jul 2016 23:31:29 you wrote: |
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> On Sunday 31 Jul 2016 23:18:00 Andrew Savchenko wrote: |
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> > On Sun, 31 Jul 2016 19:40:37 +0100 Mick wrote: |
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> > > Hi All, |
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> > > |
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> > > I am dipping my toe into cross-compile territory, in order to build i686 |
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> > > binaries for a 32bit box, which is too old to do its own emerges. I am |
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> > > using an amd64 box which is significantly faster to do all the heavy |
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> > > lifting and started applying this page: |
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> > > |
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> > > https://wiki.gentoo.org/wiki/Embedded_Handbook/General/Creating_a_cross-> > > co |
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> > > mpiler |
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> > > |
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> > > which I followed up with: |
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> > > |
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> > > https://wiki.gentoo.org/wiki/Cross_build_environment |
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> > |
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> > And here comes this misconception again... Please, tell me, why on |
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> > the earth cross-compiling is needed for amd64 to produce i686 |
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> > binaries?! |
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> |
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> I thought it did. From what you're saying I got this wrong. When I read |
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> the first use case bullet point, on the 2nd URL above, I thought I had |
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> arrived at the right place. :-/ |
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> |
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> > amd64 CPU _natively_ supports x86 instructions, amd64 kernel |
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> > natively supports x86 code (this can be disabled during kernel |
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> > config, but usually it isn't), amd64 gcc *can* produce x86 binaries. |
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> |
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> I thought amd64 can run x86 binaries, but I wasn't aware that it can compile |
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> them too, or what is needed to achieve this. My knowledge on gcc is pretty |
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> much minimal. I did search the Wiki, gentoo.org and Google for it, but all |
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> I could come across was cross-compiling. |
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> |
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> > There are two ways to help older x86 boxes to build packages faster: |
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> > |
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> > 1. Set up distcc to produce x86 code on your amd64 processors. Just |
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> > add -m32 to your *FLAGS. |
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> |
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> I read somewhere in these unsuccessful searches of mine that distcc is |
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> deprecated and it is better to use cross-compiling instead ... |
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> |
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> > 2. Copy old box system to a chroot dir on amd64. Run setarch i686 |
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> > and chroot to that directory, and build 32-bit packages as usual! |
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> > There are two ways to deliver them: |
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> > |
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> > 2.a. Generate binary packages on new box and install them on old |
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> > boxes. |
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> |
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> OK, I'll uninstall crossdev and try 2.a in the first instance. Is there a |
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> Wiki page explaining what parts of the x86 system are needed to carry |
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> across to the amd64 guest_root_fs? I wouldn't think I will need the whole |
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> x86 fs? Anything else I need to pay attention to? |
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> |
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> > 2.b. Instead of copying old box's root, mount it over NFS. |
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> |
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> I'll look into this later, after I get 2.a going. |
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> |
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> > I'm currently using 1, but planning to switch to 2.a, because |
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> > distcc can't help with everything (execution of java, python, |
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> > autotools and other stuff can't be helped with distcc). |
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> > |
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> > I used 2.b earlier on very old box (it is dead now). |
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> > |
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> > 3. Well, one can do full cross-compilation as you proposed, but |
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> > this is ridiculous. Cross-compilation is always a pain and if it |
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> > can be avoided, it should be avoided. |
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> |
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> Thanks for this advice. I am not particularly interested to use crossdev if |
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> it is not the best suited tool for the job, but I wasn't aware of the |
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> alternatives you suggested and haven't as yet found any HOWTOs on it. |
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|
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Given Andrew's steer I had another look and found this guide: |
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|
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https://wiki.gentoo.org/wiki/Project:AMD64/32-bit_Chroot_Guide |
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|
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Is this approach still valid, or have things moved on since this article was |
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authored (2012) and different configuration/approach is now recommended? |
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|
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-- |
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Regards, |
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Mick |