Re: git: 9cc06bf7aa28 - main - amd64 GENERIC: Switch uart hints from "isa" to "acpi"

On 7/15/24 15:15, John Baldwin wrote:
> The branch main has been updated by jhb:
> 
> URL: https://cgit.FreeBSD.org/src/commit/?id=9cc06bf7aa2846c35483de567779bb8afc289f53
> 
> commit 9cc06bf7aa2846c35483de567779bb8afc289f53
> Author:     John Baldwin <jhb@FreeBSD.org>
> AuthorDate: 2024-07-15 19:14:01 +0000
> Commit:     John Baldwin <jhb@FreeBSD.org>
> CommitDate: 2024-07-15 19:15:29 +0000
> 
>      amd64 GENERIC: Switch uart hints from "isa" to "acpi"
>      
>      This causes these hints to be only used to wire device unit numbers
>      for serial ports enumerated by ACPI but will not create ISA device
>      nodes if ACPI doesn't enumerate them.  Note that IRQ hints are not
>      used for wiring so have been removed.
>      
>      PR:             270707
>      Reported by:    aixdroix_OSS@protonmail.com, Michael Dexter
>      Reported by:    mfw_burn@pm.me, Hannes Hfauswedell <h2+fbsdports@fsfe.org>
>      Reported by:    Matthias Lanter <freebsd@lanter-it.ch>
>      Reported by:    William Bulley <web@umich.edu>
>      Reviewed by:    imp
>      MFC after:      1 week
>      Differential Revision:  https://reviews.freebsd.org/D45945
> ---
>   sys/amd64/conf/GENERIC.hints | 6 ++----
>   1 file changed, 2 insertions(+), 4 deletions(-)
> 
> diff --git a/sys/amd64/conf/GENERIC.hints b/sys/amd64/conf/GENERIC.hints
> index 7c2a3f28b9ce..4f6121c7cf77 100644
> --- a/sys/amd64/conf/GENERIC.hints
> +++ b/sys/amd64/conf/GENERIC.hints
> @@ -6,13 +6,11 @@ hint.psm.0.at="atkbdc"
>   hint.psm.0.irq="12"
>   hint.sc.0.at="isa"
>   hint.sc.0.flags="0x100"
> -hint.uart.0.at="isa"
> +hint.uart.0.at="acpi"
>   hint.uart.0.port="0x3F8"
>   hint.uart.0.flags="0x10"
> -hint.uart.0.irq="4"
> -hint.uart.1.at="isa"
> +hint.uart.1.at="acpi"
>   hint.uart.1.port="0x2F8"
> -hint.uart.1.irq="3"
>   hint.atrtc.0.at="isa"
>   hint.atrtc.0.port="0x70"
>   hint.atrtc.0.irq="8"

Warner would like to purge more of this file (almost all of it) which is
probably correct.  Warner believes that the uart0 flags to set serial
console aren't needed for loaders from FreeBSD 9+ due to the hw.uart.*
tunables modern loaders set.  I'm less certain about hints for "fixed"
devices such as attimer0, atrtc0, and atkbdc0.  I feel like some systems
have failed to enumerate those in the past, though such systems may be
i386-only.  The sc0 hints I think can go away once we fully deprecate
sc(4) in favor of only vt(4).

I've chosen to leave i386 alone as there's still some ancient i386 cruft,
but on amd64 we have a higher bar (e.g. ACPI is de facto required for
amd64).  Also, i386 kernels have one foot in the grave already.

This commit is also somewhat narrow in scope as I plan to merge it back
to 13 and 14.

-- 
John Baldwin