hint.uart.1 in device.hints causes freeze at boot

[Warner Losh]

On Fri, Feb 26, 2016 at 6:49 PM, Marcel Moolenaar <marcel at xcllnt.net> wrote:

>
> > On Feb 26, 2016, at 7:48 AM, Lundberg, Johannes <
> johannes at brilliantservice.co.jp> wrote:
> >
> > Hi
> >
> > Not sure if it's ok to cross post but I wasn't sure which list to send
> to.
> >
> > On Intel Atom X5-Z8300 SoC (CherryTrail) the install memstick image
> (amd64)
> > halts during boot because of uart.1 settings in device hints.
>
> I have found that FreeBSD’s default device.hints file has fallen
> behind on reality and is indeed causing problems on more modern
> H/W, like the H/W you mention.
>
> >
> > I'm sure it is there for a reason so what is the alternative actions? Is
> > the solution to get a bootable Atom SoC image to create yet another
> > distribution or can the installer choose the proper device.hints
> > dynamically during boot?
>
> FreeBSD should really get rid of any default hints by now; or at least
> limit the hints to what is absolutely certain to be needed or to be
> correct.
>

Any reason not to add .disabled=1 to all the entries that are there,
with the possible exception of uart.0? At least for i386 and amd64?
Bonus points for writing code that filters those out when there's
no ACPI. While PNPBIOS could also supply this info, I doubt that you
could find hardware that has pnpbios data and not ACPI data except
maybe some of the soekris boxes to test against.

Better still would be to split the current GENERIC.hints into two bits.
One that was strictly for legacy (!ACPI and !PNPBIOS) situations, and
one that we always load. There look to be at least a couple of hints
that are universally relevant still. I might have a 200MHz pentium I
can test this with...

As near as I can tell, only the following are relevant:
hint.fd.0.at="fdc0"
hint.fd.0.drive="0"
hint.fd.1.at="fdc0"
hint.fd.1.drive="1"
hint.acpi_throttle.0.disabled="1"
hint.p4tcc.0.disabled="1"

and maybe

hint.apm.0.disabled="1"

The floppy is for systems that have it, but won't add a floppy controller.
APM hasn't been relevant since ~100MHz Pentium. The last two I'm
unsure of.

Warner

Warner