Hi Huacai,
Please stop top-posting - you make it difficult to reply. I know you've
mentioned difficulties sending mail from your @lemote.com address but no
matter which email address you're using you should be able to format
your email properly if you're using a suitable email client.
On Tue, Jun 19, 2018 at 02:50:36PM +0800, 陈华才 wrote:
> > I think it'd be neater if we did this from C in cpu_probe_loongson()
> > though. If we add __BUILD_SET_C0(config6) to asm/mipsregs.h and define a
> > macro naming the SFB enable bit then both boot CPU & secondary cases
> > could be handled by a single line in cpu_probe_loongson(). Something
> > like this:
> >
> > set_c0_config6(LOONGSON_CONFIG6_SFB_ENABLE);
> >
> > Unless there's a technical reason this doesn't work I'd prefer it to the
> > assembly version (and maybe we could move the LPA & ELPA configuration
> > into cpu-probe.c too then remove asm/mach-loongson64/kernel-entry-init.h
> > entirely).
>
> We should enable SFB/ELPA as early as possible, because it is
> dangerous if one core is SFB-enabled why another core isn't. ELPA is
> similar.
Why is it dangerous, and in what circumstances?
Based on commit messages & our other discussions about the SFB my
understanding is that it sits within a core, between the CPU pipeline &
the core's L1 data cache. Why would another core care about it being
enabled or disabled? How could the other core even tell?
Thanks,
Paul
