RFR: JDK-8158502: aarch32: detect QEMU user-mode emulation

[Andrey Petushkov]

Hi Ed!

Cool, thank you, did not know such thing exists! Since it’s available since kernel 3.1 IMHO it’s ok to rely on it. I will give it a try after finish with v6k

Regards,
Andrey

> On 08 Jun 2016, at 18:05, Edward Nevill <edward.nevill at gmail.com> wrote:
> 
> Hi,
> 
> Is it possible to use the kernel user helper functions to implement the
> required functionality for ldrexd/strexd?
> 
> https://www.kernel.org/doc/Documentation/arm/kernel_user_helpers.txt
> 
> I am thinking of __kuser_cmpxchg64
> 
> Regards,
> Ed.
> 
> On Wed, 2016-06-08 at 17:41 +0300, Andrey Petushkov wrote:
>> Hi Alex,
>> 
>> Thank you! And you’re seem to be right, ARM1136 seem to be “pure” v6, without extensions brought by v6k. One problem though, it is soft-float as you say. And to my best knowledge our port is not ready for pure soft-float environment. It does not respect soft-float ABI. In addition, I’ve stumbled across one unpleasant problem of missing ldrexd/strext instruction in v6. So I might reconsider support of pure v6, at least for the time being. So please hold off from setting up this machine, until further notice.
>> At the same time support for v6k remains my first priority so keep your RPi B+ warmed :)
>> (I've finished the detection code and started battle against relocations)
>> 
>> Regards,
>> Andrey
>> 
> 
>