Re: SPCR and default serial port

From: Jon Masters
Date: Fri Apr 17 2020 - 02:34:27 EST


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