Re: (tiny) patch review: return if RTC diag fails

[Emile `iMil' Heitor <imil%home.imil.net@localhost>]

On Fri, 14 Feb 2025, Manuel Bouyer wrote:

> > (also it should be specific to the broken hypervisor concerned and not
> > applied to all hypervisors)
>
> that's what VM_GUEST_* is for

This behavior is specific to the microvm machine type in QEMU, which
sets rtc=off by default, we can't just have a condition on the
hypervisor.

As a matter of fact we do have a validity/presence test in
sys/arch/x86/isa/rtc.c rtcget():

if ((mc146818_read(NULL, MC_REGD) & MC_REGD_VRT) == 0)
	return (-1);

ref https://www.scs.stanford.edu/23wi-cs212/pintos/specs/mc146818a.pdf
page 16 (thanks khorben@ for the hint).

Can't we just move this test to startrtclock()?

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Emile `iMil' Heitor <imil@{home.imil.net,NetBSD.org}> | https://imil.net