Re: [PATCH] hw/display/tcx: Init memory regions in realize

[Thomas Huth <thuth@redhat.com>]

On 16/03/2026 17.06, Peter Xu wrote:
> On Mon, Mar 16, 2026 at 02:06:51PM +0100, BALATON Zoltan wrote:
>> Due to aux-ram-share property qemu_ram_alloc_internal dereferences
>> current_machine which is not set during init when inspecting the
>> device. This causes the qtest/device-introspect-test to fail since a
> 
> Does it has anything to do with aux-ram-share?  I thought it's because the
> qom introspect test will create yet another sun-tcx device, causing double
> registration?

I think it happens because the test starts QEMU with the sun4m machine (or 
whichever machine uses this device by default), and then creates another 
instance of the device for introspection (without realizing it). You can 
easily recreate the bug manually like this:

  $ ./qemu-system-sparc -M SS-20 -display none -monitor stdio
  QEMU 10.2.50 monitor - type 'help' for more information
  (qemu) device_add sun-tcx,help
  RAMBlock "tcx.prom" already registered, abort!
  Aborted (core dumped)

An instance_init() function should not change the global state of QEMU, so 
registering memory regions this way is a no-go. This has to be done in 
realize() instead.

So for this patch here:
Reviewed-by: Thomas Huth <thuth@redhat.com>