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Re: Using %stick where available


On Nov 7, 2012, at 7:04 AM, Takeshi Nakayama wrote:

Michael <macallan%netbsd.org@localhost> wrote


the attached patch adds support for the system timer interrupt present
in UltraSPARC-III and some later II ( like IIe and IIi with on chip
ecache ). It hasn't seen much testing beyond 'works on my Blade 2500'.
The purpose is to have a timer interrupt / time counter that's
independent of the CPU's clock rate, so we can change it without
worrying about time keeping.

It looks ok to me, but as Eric reported it needs some fix.

Yeah, I have no US-IIe hardware so I couldn't test it there, which is one of the reasons why I posted the patch here first.

+       struct cpu_info *ci = curcpu();

Replace the following curcpu()s with ci.


I think the following is better for consistency.

-       long clk;
+       long clk, sclk;

Yeah, I left it an int because that's what we get from the PROM, but you're right, they should be the same type.

+       sclk = prom_getpropint(findroot(), "stick-frequency", 0);
+       ci->ci_system_clockrate[0] = sclk;
+       ci->ci_system_clockrate[1] = sclk / 1000000;

US-IIe has system tick register, but its implementation is
different to US-III one.  It can be used via memory mapped system
registers, not via ancillary state register (%asr24).

I expected trouble with US-IIe but not quite like that.

So, I suggest not to use it on US-IIe as below.

        if (!CPU_IS_HUMMINGBIRD()) {
                sclk = prom_getpropint(findroot(), "stick-frequency", 0);
                ci->ci_system_clockrate[0] = sclk;
                ci->ci_system_clockrate[1] = sclk / 1000000;

Done, slightly changed to make sure ci_system_clockrate[] is 0 if we don't have %stick.

And, put the following into include/psl.h.

define  CI_CLOCKRATE    offsetof(struct cpu_info, ci_cpu_clockrate)
+define CI_SYSCLOCKRATE offsetof(struct cpu_info, ci_system_clockrate)
define  CI_IDEPTH       offsetof(struct cpu_info, ci_idepth)
define  CI_INTRPENDING  offsetof(struct cpu_info, ci_intrpending)
define  CI_TICK_IH      offsetof(struct cpu_info, ci_tick_ih)


I put it there because CI_CLOCKRATE is used in delay() which we may want to adapt to %stick / CI_SYSCLOCKRATE at some point. I'll leave it out in the revised patch.

+ * setstick(long)
+ */
+       retl
+        wr %o0, STICK
+ * long getstick(void)
+ */
+       retl
+        rd STICK, %o0

I'll replace them with inline functions like settick/gettick after you commited.

I put them there because I couldn't get the inline assembler to do what I want ( serious lack of practice on my part )

BB_ERRATA_1 is an errata of US-II, so #ifdef BB_ERRATA_1 cases are

Removed them.

Attached is the revised patch, thanks for looking at this!

have fun

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