possible deprecation and removal of some old QEMU Arm machine types (pxa2xx, omap, sa1110)

[Peter Maydell]

QEMU includes some models of old Arm machine types which are
a bit problematic for us because:
 * they're written in a very old way that uses numerous APIs that we
   would like to get away from (eg they don't use qdev, they use
   qemu_system_reset_request(), they use vmstate_register(), etc)
 * they've been that way for a decade plus and nobody particularly has
   stepped up to try to modernise the code (beyond some occasional
   work here and there)
 * we often don't have test cases for them, which means that if we
   do try to do the necessary refactoring work on them we have no
   idea if they even still work at all afterwards

All these machine types are also of hardware that has largely passed
away into history and where I would not be surprised to find that
e.g. the Linux kernel support was never tested on real hardware
any more.

So I would like to explore whether we can deprecate-and-drop
some or all of them. This would let us delete the code entirely
rather than spending a long time trying to bring it up to scratch
for a probably very small to nonexistent userbase. The aim of this
email is to see if anybody is still using any of these and would be
upset if they went away. Reports of "I tried to use this machine
type and it's just broken" are also interesting as they would
strongly suggest that the machine has no real users and can be
removed.

The machines I have in mind are:

PXA2xx machines:

akita                Sharp SL-C1000 (Akita) PDA (PXA270)
borzoi               Sharp SL-C3100 (Borzoi) PDA (PXA270)
connex               Gumstix Connex (PXA255)
mainstone            Mainstone II (PXA27x)
spitz                Sharp SL-C3000 (Spitz) PDA (PXA270)
terrier              Sharp SL-C3200 (Terrier) PDA (PXA270)
tosa                 Sharp SL-6000 (Tosa) PDA (PXA255)
verdex               Gumstix Verdex Pro XL6P COMs (PXA270)
z2                   Zipit Z2 (PXA27x)

OMAP1 machines:

cheetah              Palm Tungsten|E aka. Cheetah PDA (OMAP310)
sx1                  Siemens SX1 (OMAP310) V2
sx1-v1               Siemens SX1 (OMAP310) V1

OMAP2 machines:

n800                 Nokia N800 tablet aka. RX-34 (OMAP2420)
n810                 Nokia N810 tablet aka. RX-44 (OMAP2420)

The one SA1110 machine:

collie               Sharp SL-5500 (Collie) PDA (SA-1110)

Obviously if we can remove all the machines that used a given
SoC, that's much more effective than if we just delete one or two.

I don't have any test images for the SA1110 or OMAP1 machines,
so those are the ones I am most keen to be able to drop.
I do have test images for a few of the pxa2xx and the OMAP2 machines.

thanks
-- PMM