SPCR and default serial port

SPCR and default serial port

[Herrenschmidt, Benjamin]

Hi !

Today, arm64 allows the serial port specified in ACPI SPCR table to be
selected as a default console, but x86 doesn't (second argument to
acpi_parse_spcr).

I understand while we might have been worried of breaking existing
setups back then but should we re-think this, maybe via a CONFIG option
?

It makes a lot of sense to have firmware tell us which of the
potentially many serial port in a system is our active console, along
with its configuration...

This also shouldn't cause problem on systems that already specify a
console explicitly on the command line.

Any opinion ?

Cheers,
Ben.

Re: SPCR and default serial port

[Jon Masters]

On 4/15/20 2:04 AM, Herrenschmidt, Benjamin wrote:
> Hi !
> 
> Today, arm64 allows the serial port specified in ACPI SPCR table to be
> selected as a default console, but x86 doesn't (second argument to
> acpi_parse_spcr).
> 
> I understand while we might have been worried of breaking existing
> setups back then but should we re-think this, maybe via a CONFIG option
> ?
> 
> It makes a lot of sense to have firmware tell us which of the
> potentially many serial port in a system is our active console, along
> with its configuration...
> 
> This also shouldn't cause problem on systems that already specify a
> console explicitly on the command line.
> 
> Any opinion ?

I think it would be /great/ if x86 followed Arm. A config option would 
allow it to be easily ignored by those who don't want it, but you'll 
want to get data from e.g. distros on how many systems have weird BIOSes 
that provide a non-useful table today.

Jon.

-- 
Computer Architect