[Letux-kernel] jz4730-i2c - clocksource

[Paul Boddie]

Nikolaus,

Going back almost a month here, but I recently saw this message:

"Unhandled EFAULT with letux kernels built with newer gcc compilers"

https://groups.google.com/g/mips-creator-ci20-dev/c/SqjtFOXT62Y

Now, the problem is related to futex_detect_cmpxchg, which sounds as if it is 
the method by which the kernel detects whether it can use the appropriate 
load-link/store-conditional instruction. And this reminded me of the 
following:

On Saturday, 6 March 2021 18:07:58 CEST H. Nikolaus Schaller wrote:
> Hi Paul,
> 
> > Am 06.03.2021 um 16:55 schrieb Paul Boddie <paul at boddie.org.uk>:
> > 
> > A brief look at arch/mips/include/asm/futex.h indicates that the LL/SC
> > (https://en.wikipedia.org/wiki/Load-link/store-conditional) instruction is
> > required for futex support. I am not sure this is provided on the JZ4730
> > or
> > even on other early XBurst1 CPUs.
> 
> Oh, interesting! Maybe we have hit some fundamental issue here.

It seems like others have encountered what they believe is a compiler bug, but 
I seem to remember that you still use GCC 4.9 or something fairly old. But I 
thought it might be useful to hear about this.

Also, there was a message about the CI20 only using 256MB of RAM with one of 
your kernels:

https://groups.google.com/g/mips-creator-ci20-dev/c/gNsIXU7cg6g

I don't remember if you saw this already.

Regards,

Paul