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

[Gordan Bobic]

Milorad already stated that cross compiling wasn't working out for him.

On Fri, Dec 23, 2016 at 6:53 PM, Dan Mick <dan.mick at redhat.com> wrote:

> I've heard some say that crosscompiling is a big win
>
> Sent from Nine <http://www.9folders.com/>
> ------------------------------
> *From:* Gordan Bobic <gordan at redsleeve.org>
> *Sent:* Dec 23, 2016 10:38 AM
> *To:* Conversations around CentOS on ARM hardware
> *Subject:* Re: [Arm-dev] How to chroot from x86 to arm?
>
> 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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