Re: OpenMPIC controller emulation in qemu ?

On Wed, May 15, 2024 at 5:09 PM Andrew Randrianasulu <randrianasulu@gmail.com> wrote:

I was researching why SMP was disabled in NewWorld mac99 machine in qeumu

There was request some time ago about SMP support ...

https://mail.gnu.org/archive/html/qemu-devel/2023-12/msg00907.html

anyway i digged around a bit and found evidence both freeBSD and openBSD supported SMP on real G4 Macs ...

https://svnweb.freebsd.org/base?view=revision&revision=209767

http://www.undeadly.org/cgi?action="">

and linux at least in 3.x days

https://ubuntuforums.org/archive/index.php/t-1947450.html
====
# cat /proc/cpuinfo
processor : 0
cpu : 7400, altivec supported
temperature : 31-33 C (uncalibrated)
clock : 500.000000MHz
revision : 2.9 (pvr 000c 0209)
bogomips : 49.81

processor : 1
cpu : 7400, altivec supported
temperature : 27-29 C (uncalibrated)
clock : 500.000000MHz
revision : 2.9 (pvr 000c 0209)
bogomips : 49.81

total bogomips : 99.63
timebase : 24907667
platform : PowerMac
model : PowerMac3,3
machine : PowerMac3,3
motherboard : PowerMac3,3 MacRISC2 MacRISC Power Macintosh
detected as : 65 (PowerMac G4 AGP Graphics)
pmac flags : 00000014
L2 cache : 1024K unified
pmac-generation : NewWorld
Memory : 1536 MB
=====

so i looked into Linux src

https://elixir.bootlin.com/linux/latest/source/arch/powerpc/platforms/powermac/pic.c
https://elixir.bootlin.com/linux/latest/source/arch/powerpc/platforms/powermac/smp.c

may be I misread some lines but i think it says while timebase freezing normally done via gpio device there IS software fallback?
====
/*
 * SMP G4 use a GPIO to enable/disable the timebase.
 */

static unsigned int core99_tb_gpio;	/* Timebase freeze GPIO */

static void smp_core99_gpio_tb_freeze(int freeze) 
"static void __init smp_core99_setup_i2c_hwsync(int ncpus)"
- i2c was for g5/64 bit CPUs / systems ...
====

also, apparently two MPICs can be cascaded for > 64 iIRQs ...but is it the case on ANY smp-capable powermac3.x ?

There is github source of darwin driver from Apply, but it all c++ ..

https://github.com/apple-oss-distributions/AppleMPIC/blob/AppleMPIC-1.0/AppleMPIC.cpp

So .. if anyone know any details about what else (apart from nr_cpu property on openpic controller) might be missing for smp emulation - I can try your ideas :) on MacOS 10.4.11 and Debian 8.1 virtual installs ...

So I hacked it a bit just to see what broke

bash-5.1$ diff -u ~/botva/src/src/qemu/hw/ppc/mac_newworld.c hw/ppc/mac_newworld.c
--- /home/guest/botva/src/src/qemu/hw/ppc/mac_newworld.c 2024-03-27 06:44:12.068828324 +0300
+++ hw/ppc/mac_newworld.c 2024-05-16 00:53:26.345222034 +0300
@@ -368,9 +368,13 @@
qdev_prop_set_chr(dev, "chrA", serial_hd(0));
qdev_prop_set_chr(dev, "chrB", serial_hd(1));

+pic_dev = DEVICE(object_resolve_path_component(macio, "pic"));
+ qdev_prop_set_uint32(pic_dev, "nb_cpus", machine->smp.cpus);
+
+
pci_realize_and_unref(PCI_DEVICE(macio), pci_bus, &error_fatal);

- pic_dev = DEVICE(object_resolve_path_component(macio, "pic"));
+
for (i = 0; i < 4; i++) {
qdev_connect_gpio_out(uninorth_pci_dev, i,
qdev_get_gpio_in(pic_dev, 0x1b + i));
@@ -575,7 +579,7 @@
mc->init = ppc_core99_init;
mc->block_default_type = IF_IDE;
/* SMP is not supported currently */
- mc->max_cpus = 1;
+ mc->max_cpus = 2;
mc->default_boot_order = "cd";
mc->default_display = "std";
mc->default_nic = "sungem";

and

bash-5.1$ diff -u ~/botva/src/src/qemu/hw/intc/openpic.c hw/intc/openpic.c
--- /home/guest/botva/src/src/qemu/hw/intc/openpic.c 2024-01-06 05:14:26.186344157 +0300
+++ hw/intc/openpic.c 2024-05-16 00:58:14.489226704 +0300
@@ -1584,8 +1584,8 @@
opp->mpic_mode_mask = GCR_MODE_MIXED;

if (opp->nb_cpus != 1) {
- error_setg(errp, "Only UP supported today");
- return;
+ //error_setg(errp, "Only UP supported today");
+ //return;
}

map_list(opp, list_le, &list_count);

and openfirmware starts ....

bash-5.1$ build/qemu-system-ppc -M mac99 -smp 2 -nographic

>> =============================================================
>> OpenBIOS 1.1 [Mar 7 2023 22:21]
>> Configuration device id QEMU version 1 machine id 1
>> CPUs: 2
>> Memory: 128M
>> UUID: 00000000-0000-0000-0000-000000000000
>> CPU type PowerPC,G4
milliseconds isn't unique.
Welcome to OpenBIOS v1.1 built on Mar 7 2023 22:21
Trying hd:,\\:tbxi...
Trying hd:,\ppc\bootinfo.txt...
Trying hd:,%BOOT...
No valid state has been set by load or init-program

0 >

but boooting finnix fails:

bash-5.1$ build/qemu-system-ppc -M mac99 -smp 2 -nographic -cdrom ~/finnix-ppc-110.iso -boot d

>> =============================================================
>> OpenBIOS 1.1 [Mar 7 2023 22:21]
>> Configuration device id QEMU version 1 machine id 1
>> CPUs: 2
>> Memory: 128M
>> UUID: 00000000-0000-0000-0000-000000000000
>> CPU type PowerPC,G4
milliseconds isn't unique.
Welcome to OpenBIOS v1.1 built on Mar 7 2023 22:21
Trying cd:,\\:tbxi...
>> switching to new context:

я:interpret: exception -13 caught

=====

so any idea how I should extend this Keylargo controller ? :)

From:	Andrew Randrianasulu
Subject:	Re: OpenMPIC controller emulation in qemu ?
Date:	Thu, 16 May 2024 01:22:19 +0300