[Arm-dev] How to chroot from x86 to arm?

[Gordan Bobic]

Userspace emulation won't be meaningfully faster. There is no real
alternative to getting a faster ARM machine.

On the cheaper end, an decently specced 8 core (4+4) can be had for under
$200. Samsung Chromebook 2 is more expensive but I find it more convenient.

On the higher end, a Gigabyte MP30-AR0/AR1 is a monster and it takes
standard DDR3 DIMMs, but it is quite expensive. I got one specifically for
compiling packages. If you decide to go down that route, if you rebuild the
kernel with the more reasonable 4KB page size, you can run a 32-bit chroot
or docker container on an aarch64 host (that is the setup I use). I filled
mine up with 128GB of RAM, so even bloadware like LibreOffice and web
browsers can compile entirely on tmpfs, which helps significantly.


On Fri, Dec 23, 2016 at 6:18 PM, Stephen John Smoogen <smooge at gmail.com>
wrote:

> On 23 December 2016 at 02:35, mo.ucina <mo.ucina at gmail.com> wrote:
> > Hello Guys,
> >
> > I have been doing centos package compiling on arm hardware for a while
> now ,
> > and it has been going OK . One drawback is that some bigger packages
> would
> > run for 10hrs to compile . I would like to speed up that process , and
> > compile on a much more powerful machine . I tried cross-compiling but
> ended
> > up with issues when the arm package got contaminated with i386 libraries
> no
> > matter what I tired .
> >
> > I also tried qemu VM running on my core2duo 4 core desktop machine . This
> > worked OK as packages were perfect , but it was slower to compile than
> using
> > arm hardware . Same package that took 10 hrs on arm hw , compiled for 3
> and
> > a half days on the desktop .
> >
> > My question is if I used a chroot approach to run the emulation will
> this be
> > quicker than a qemu VM . If so can anyone please share their
> instructions on
> > how to configure a chroot to run a centos 7 arm image on a x86 desktop.
>
> I am probably misunderstanding what you are wanting.. but my initial
> thought is that you can't.
>
> The ARM uses a completely different computer architecture to x86_64.
> This means that you can't just chroot into an arm environment because
> the underlying processor (x86_64) isn't changing. It is still going to
> try and interpret machine code 32 to be one thing even if on an ARM
> that meant something completely different. [Also the fact that even if
> machine code 32 was the same the ARM has different number of registers
> and other internals than an x86]
>
> You are running into the same problems we have had with ARM
> development over the last N years. The only solutions are
>
> a) Patience with the slow hardware you have.
> b) Get more hardware but still have patience
> c) Get large scale server hardware and have patience.
>
> The emulation problem you are running into is pretty much standard
> because of the translation of a RISC architecture on a CISC
> architecture. The most off the shelf ARM systems are equivalent to a
> P400 MHZ from the early 2000's in some ways but also faster in others.
> [Trying to use a P400 to compile say texlive is a multi day event
> while on an arm system it might be only 10-20 hours.]  You have a
> slightly better emulation result if you have an 64 bit arm 'emulate' a
> 32 bit arm but that is hardware dependent and still requires patience.
>
>
>
> >
> > Best Regards
> >
> > Milorad
> >
> > _______________________________________________
> > Arm-dev mailing list
> > Arm-dev at centos.org
> > https://lists.centos.org/mailman/listinfo/arm-dev
>
>
>
> --
> Stephen J Smoogen.
> _______________________________________________
> Arm-dev mailing list
> Arm-dev at centos.org
> https://lists.centos.org/mailman/listinfo/arm-dev
>
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