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Re: [PATCH-for-5.2 1/2] hw/mips/mipssim: Use MMIO serial device on fake


From: Marc-André Lureau
Subject: Re: [PATCH-for-5.2 1/2] hw/mips/mipssim: Use MMIO serial device on fake ISA I/O
Date: Tue, 1 Sep 2020 21:20:27 +0400

Hi

On Thu, Jul 30, 2020 at 9:04 PM Philippe Mathieu-Daudé <philmd@redhat.com> wrote:
The 'mipssim' is not a real hardware, it is a simulator.

There is an ISA MMIO space mapped at 0x1fd00000, however
this is not a real ISA bus (no ISA IRQ). So can not use
the TYPE_ISA_SERIAL device...
Instead we have been using a plain MMIO device, but named
it IO.

TYPE_SERIAL_IO is a superset of TYPE_SERIAL_MM, using
regshift=0 and endianness=DEVICE_LITTLE_ENDIAN.

Directly use the TYPE_SERIAL_MM device, enforcing the
regshift/endianness values. 'regshift' default is already
'0'. 'endianness' is meaningless for 8-bit accesses.

Note, there is no migration problem, because TYPE_SERIAL_IO
was not migrated.

I am not so sure about that. It has:
    /* No dc->vmsd: class has no migratable state */

but that doesn't mean it's not migratable I think.


Suggested-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Philippe Mathieu-Daudé <philmd@redhat.com>
---
 hw/mips/mipssim.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/hw/mips/mipssim.c b/hw/mips/mipssim.c
index 1b3b762203..853bbaca58 100644
--- a/hw/mips/mipssim.c
+++ b/hw/mips/mipssim.c
@@ -216,9 +216,11 @@ mips_mipssim_init(MachineState *machine)
      * MIPS CPU INT2, which is interrupt 4.
      */
     if (serial_hd(0)) {
-        DeviceState *dev = qdev_new(TYPE_SERIAL_IO);
+        DeviceState *dev = qdev_new(TYPE_SERIAL_MM);

         qdev_prop_set_chr(dev, "chardev", serial_hd(0));
+        qdev_prop_set_uint8(dev, "regshift", 0);
+        qdev_prop_set_uint8(dev, "endianness", DEVICE_LITTLE_ENDIAN);
         qdev_set_legacy_instance_id(dev, 0x3f8, 2);
         sysbus_realize_and_unref(SYS_BUS_DEVICE(dev), &error_fatal);
         sysbus_connect_irq(SYS_BUS_DEVICE(dev), 0, env->irq[4]);
--
2.21.3




--
Marc-André Lureau

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