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Re: Test atomic operations on SPARC 32-bit

Hi Adrian,

> On 12/09/2017 12:21 AM, Petr Vorel wrote:
> >> I'm asking because atomic operations were only added with SPARCv8+ and later.
> > SPARCv8 would be enough as SPARCv7 is dead. So still no hw support.

> From what I have heard, SPARCv7 should actually work since people added
> kernel helpers to the Linux kernel to emulate the atomics for v7 hardware.
Oh yes, I've heard that as well. I'm looking into kernel source

According to the sources they implemented it by hashing the object address and indexing
into an array of spinlocks.

Also LWN is talking about it

> SPARCv8 doesn't have Compare-And-Swap either, SPARCv8+ does which is what
> most people run these days when they run 32-Bit-SPARC.

> >> In any case, the Gentoo people are still on 32-Bit SPARC. You might ask there
> >> first (see #gentoo-sparc on Freenode). Otherwise, we will have to create a
> >> 32-Bit chroot for you but that would probably take a bit longer.
> > OK, I'll ask them and if not works I'll come back.

> They just started working on their SPARC port again.
Good to know, thanks!

> Adrian

Kind regards,

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