[PATCH 0/2] m68k/q800: make the GLUE chip a QOM device

[Peter Maydell <peter.maydell@linaro.org>]

This series is 6.0 material really I think.  It's a bit of cleanup
prompted by a Coverity issue, CID 1421883.  There are another half
dozen or so similar issues, where Coverity is complaining that we
allocate an array of qemu_irqs with qemu_allocate_irqs() in a board
init function -- in this case the 'pic' array in q800_init() -- and
then we return from the board init function and the memory is leaked,
in the sense that nobody has a pointer to it any more.

The leak isn't real, in that board init functions are called only
once, and the array of qemu_irqs really does need to stay around for
the life of the simulation, so these are pretty much insignificant
as Coverity issues go. But this coding style which uses a free-floating
set of qemu_irqs is not very "modern QEMU", so the issues act as
a nudge that we should clean the code up by encapsulating the
interrupt-line behaviour in a QOM device. In the q800 case there
actually is already a GLUEState struct, it just needs to be turned
into a QOM device with GPIO input lines. Patch 2 does that.

Patch 1 fixes a bug I noticed while doing this work -- it's
not valid to connect two qemu_irq lines directly to the same
input (here both ESCC irq lines go to pic[3]) because it produces
weird behaviour like "both lines are asserted but the device
consuming the interrupt sees the line deassert when one of the
two inputs goes low, rather than only when they both go low".
You need to put an explicit OR gate in, assuming that logical-OR
is the desired behaviour, which it usually is.

Tested only with 'make check' and 'make check-acceptance',
but the latter does have a q800 bootup test.

thanks
-- PMM

Peter Maydell (2):
  hw/m68k/q800: Don't connect two qemu_irqs directly to the same input
  hw/m68k/q800.c: Make the GLUE chip an actual QOM device

 hw/m68k/q800.c  | 92 ++++++++++++++++++++++++++++++++++++++++++-------
 hw/m68k/Kconfig |  1 +
 2 files changed, 80 insertions(+), 13 deletions(-)

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2.20.1