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[PATCH v2 0/8] serial: Add MMIO & SPCR support

From: Benjamin Herrenschmidt
Subject: [PATCH v2 0/8] serial: Add MMIO & SPCR support
Date: Thu, 22 Dec 2022 17:12:49 +1100

This series adds support for MMIO serial ports and auto-configuration

This is necessary for the serial port to work on AWS EC2 "metal" x86

An MMIO serial port can be specified explicitely using the
"mmio," prefix for the --port argument to the 'serial' command,
the register access size can also be specified via a suffix,
and when 'serial' is used without arguments, it will try to use
an ACPI SPCR entry (if any) to add the default port and configure
it appropriately (speed, parity etc...)

This was tested using SPCR on an actual c5.metal instance, and using
explicit instanciation via serial -p mmioXXXXXXXX on a modified qemu
hacked to create MMIO PCI serial ports and to create a SPCR ACPI table.

The insipiration was an original implementation by
Matthias Lange ! matthias.lange at
However, the code was rewritten pretty much from scratch.

v2: This version (hopefully) addresses all the review commments and
has been rebased on the latest master branch.

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