K 10
svn:author
V 8
cperciva
K 8
svn:date
V 27
2019-05-23T19:55:53.485675Z
K 7
svn:log
V 521
Use ACPI SPCR on x86

This takes the SPCR code currently in uart_cpu_arm64.c, moves it into
a new uart_cpu_acpi.c (with some associated refactoring), and uses it
from both arm64 and x86.

An SPCR serial port address AccessWidth field value of 0 ("reserved")
is now treated as 1 ("byte access") in order to work around a buggy
SPCR table on Amazon EC2 i3.metal instances.

Reviewed by:	manu, Greg V
MFC after:	3 days
Sponsored by:	https://www.patreon.com/cperciva
Differential Revision:	https://reviews.freebsd.org/D20357

END