Bug#864368: Expand kernel serial port configuration

[Dave Hansen <dave.hansen@intel.com>]

Package: linux-image-4.9.0-3-amd64
Severity: medium

When my system boots the Debian installer, it appears to hang at a blank
screen.  There are two reasons for this, and two kernel configuration
parameters need to be modified:

CONFIG_SERIAL_8250_RUNTIME_UARTS=16
CONFIG_SERIAL_8250_MID=y

There are two things that cause the apparent hang:

One, the system has only has PCI serial ports.  The traditional, legacy
serial ports (at the low I/O ports like 0x3F8) are either not present or
not connected.  The kernel is only configured for 4 runtime serial ports
 (CONFIG_SERIAL_8250_RUNTIME_UARTS=4).  But, all 4 of those ports are
used for the legacy ports leaving no room for the PCI serial port.

Please raise:

	CONFIG_SERIAL_8250_RUNTIME_UARTS

to something larger, perhaps 16 or 8, such as:

	CONFIG_SERIAL_8250_RUNTIME_UARTS=16

The second issue is that the "mid" serial driver is not configured in
this package.  Please add the "8250_MID" driver by default and have it
built in (as opposed to being as a module).  Some systems which have
serial ports driven by this driver have *only* these ports.  They have
no other output devices.  Having it built in is the only way to diagnose
and fix boot issues that occur before modules start being loaded.

The necessary option is:

	CONFIG_SERIAL_8250_MID=y

While the 4.9 kernel is the most important one to see these options
changed, it would also be handy to have these options added for other
packages.  Should I submit separate bugs from those?