Re: [crosstool-ng/crosstool-ng] 1f5906: samples: add aarch64-rpi3-linux-gnueabi

[Mike Ray <mike@raspberryvi.org>]

On 04/03/2016 00:31, Bryan Hundven wrote:
> 
>> On Mar 3, 2016, at 4:25 PM, Bryan Hundven <bryanhundven@gmail.com> wrote:
>>
>>>
>>> On Mar 3, 2016, at 12:33 PM, Mike Ray <mike@raspberryvi.org> wrote:
>>>
>>> On 03/03/2016 17:13, Bryan Hundven wrote:
>>>> Branch: refs/heads/master
>>>> Home:   https://github.com/crosstool-ng/crosstool-ng
>>>> Commit: 1f590667acc1dc1f729c3f4c14612399100f041d
>>>>     https://github.com/crosstool-ng/crosstool-ng/commit/1f590667acc1dc1f729c3f4c14612399100f041d
>>>> Author: Bryan Hundven <bryanhundven@gmail.com>
>>>> Date:   2016-03-03 (Thu, 03 Mar 2016)
>>>>
>>>> Changed paths:
>>>>   A samples/aarch64-rpi3-linux-gnueabi/crosstool.config
>>>>   A samples/aarch64-rpi3-linux-gnueabi/reported.by
>>>>
>>>> Log Message:
>>>> -----------
>>>> samples: add aarch64-rpi3-linux-gnueabi
>>>>
>>>> This is a aarch64 raspberry pi 3 sample.
>>>>
>>>> Please test!
>>>>
>>>> Signed-off-by: Bryan Hundven <bryanhundven@gmail.com>
>>>>
>>>>
>>>> Commit: bd460e8872ddc7dbbdcb09c2c0a18d22936bf698
>>>>     https://github.com/crosstool-ng/crosstool-ng/commit/bd460e8872ddc7dbbdcb09c2c0a18d22936bf698
>>>> Author: Bryan Hundven <bryanhundven@gmail.com>
>>>> Date:   2016-03-03 (Thu, 03 Mar 2016)
>>>>
>>>> Changed paths:
>>>>   A samples/aarch64-rpi3-linux-gnueabi/crosstool.config
>>>>   A samples/aarch64-rpi3-linux-gnueabi/reported.by
>>>>
>>>> Log Message:
>>>> -----------
>>>> Merge pull request #362 from bhundven/rpi_aarch64_sample
>>>>
>>>> samples: add aarch64-rpi3-linux-gnueabi
>>>>
>>>>
>>>> Compare: https://github.com/crosstool-ng/crosstool-ng/compare/0f76cad2f078...bd460e8872dd
>>>>
>>>>
>>>>
>>>> --
>>>> For unsubscribe information see http://sourceware.org/lists.html#faq
>>>>
>>>
>>> Hello.
>>>
>>> Toolchain built and helloworld app compiled.
>>>
>>> Not sure if you intended for the name of the sample to be prefixed
>>> 'aarch' instead of 'arch':
>>>
>>> 	aarch64-rpi3-linux-gnueabi/
>>
>> Yes, aarch64. It’s “arm arch 64” ;)
>> They also call arm 32-bit aarch32, but config.sub still search for arm* instead of aarch32.
>>
>>>
>>> Output of `file helloworld`:
>>>
>>> 	helloworld: ELF 64-bit LSB executable, ARM aarch64, version 1 (SYSV),
>>> dynamically linked, interpreter /lib/ld-linux-aarch64.so.1, for
>>> GNU/Linux 4.0.4, not stripped
>>
>> Looks good!
>>
>>>
>>> Built on 64-bit Debian Jessie.
>>>
>>> Of course helloworld won't run on my Pi3 with 32-bit Raspbian.
>>
>> Right.
>>
>>>
>>> Did you intend this sample to not be hard-float? (I don't know whether
>>> the Cortex A53 is HF or not).
>>
>> Dang, I new I felt like I was jumping the gun when I merged. I’ll fix that.
> 
> And that is a nope:
> (Quoting ARM.com)
> Hard-float ABI by default in ARMv8-A
> 
> So we should be good here.
> 
>>
>>>
>>> There is some debate on the Foundation site whether running 64-bit with
>>> only 1GB of RAM is much of a gain but it will be interesting finding out.
>>
>> It’s true. There really isn’t much bonus to running in 64-bit mode without more memory.
>>
>>>
>>> Foundation forum mods and developers haven't mentioned whether
>>> boot-loader needs to be 64-bit as well.
>>
>> Are they releasing 64-bit firmware files?
>>
>>>
>>> Mike
>>
>> Cheers,
>>
>> -Bryan
> 
> Cheers,
> 
> -Bryan
> 

I haven't seen anything on the Foundation forum pages that suggest there
are any plans at the moment to do so, apart from someone saying the
'Raspbian guys are investigating the possibility".

I have no idea whether the boot-loader is bitness-independent or not,
but I found no suggestion it isn't.

I don't know much about the finer points of architectures but I will
give a kernel compile a go (when I have recreated the toolchain with HF)
just for the hell of it.  It'll probably crash and burn.

Mike



-- 
Michael A. Ray
Analyst/Programmer
Witley, Surrey, South-east UK

Eyes-free Linux:
http://eyesfreelinux.ninja/

Raspberry VI:
http://www.raspberryvi.org/


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