[Qemu-devel] [PATCH 0/3] serial: fixes for migration

[Paolo Bonzini <pbonzini@redhat.com>]

While adding migration support for thr_ipending, I and Pavel chose
the default value of thr_ipending (absent the subsection) according
to what should be the common behavior of the serial device and its
drivers.

However, the condition did not actually match the common state of the
serial device because of emulation inaccuracies.  Thus the subsection
is almost always transmitted, which breaks migration from 2.2 to 2.1.

Patch 3 fixes these inaccuracies, but unmasks a missed interrupt bug
that upsets Windows.  In order to keep bisectability, that missed
interrupt is first fixed in patch 2.  And to close the circle, patch 1
cleans up more code that didn't match the datasheet too well (and was
also unnecessarily complicated); that was the first, unfruitful attempt
to fix the bug.

Datasheet available at http://www.ti.com/lit/ds/symlink/pc16550d.pdf

Paolo Bonzini (3):
  serial: fix THRE/TEMT handling
  serial: update LSR on enabling/disabling FIFOs
  serial: do not trigger THR interrupt after writing to IER

 hw/char/serial.c | 34 ++++++++++++++++------------------
 1 file changed, 16 insertions(+), 18 deletions(-)

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1.8.3.1