Re: [PATCH v3] ppc/amigaone: Allow running AmigaOS without firmware image

[Cédric Le Goater]

On 11/28/23 02:32, BALATON Zoltan wrote:

The machine uses a modified U-Boot under GPL license but the sources
of it are lost with only a binary available so it cannot be included
in QEMU. Allow running without the firmware image which can be used
when calling a boot loader directly and thus simplifying booting
guests. We need a small routine that AmigaOS calls from ROM which is
added in this case to allow booting AmigaOS without external firmware
image.

Signed-off-by: BALATON Zoltan <bala...@eik.bme.hu>

Since this is 8.2 material :


Fixes: d9656f860a38 ("hw/ppc: Add emulation of AmigaOne XE board")


Thanks,

C.

---
v3: Instead of -bios none do this when no -bios option given, use
constants for address and rom_add_blob_fixed() to add dummy_fw.
This makes both code and usage a bit simpler.

  hw/ppc/amigaone.c | 35 +++++++++++++++++++++++------------
  1 file changed, 23 insertions(+), 12 deletions(-)

diff --git a/hw/ppc/amigaone.c b/hw/ppc/amigaone.c
index 992a55e632..ddfa09457a 100644
--- a/hw/ppc/amigaone.c
+++ b/hw/ppc/amigaone.c
@@ -36,10 +36,19 @@
   * -device VGA,romfile=VGABIOS-lgpl-latest.bin
   * from http://www.nongnu.org/vgabios/ instead.
   */
-#define PROM_FILENAME "u-boot-amigaone.bin"
  #define PROM_ADDR 0xfff00000
  #define PROM_SIZE (512 * KiB)

+/* AmigaOS calls this routine from ROM, use this if no firmware loaded */

+static const char dummy_fw[] = {
+    0x38, 0x00, 0x00, 0x08, /* li      r0,8 */
+    0x7c, 0x09, 0x03, 0xa6, /* mtctr   r0 */
+    0x54, 0x63, 0xf8, 0x7e, /* srwi    r3,r3,1 */
+    0x42, 0x00, 0xff, 0xfc, /* bdnz    0x8 */
+    0x7c, 0x63, 0x18, 0xf8, /* not     r3,r3 */
+    0x4e, 0x80, 0x00, 0x20, /* blr */
+};
+
  static void amigaone_cpu_reset(void *opaque)
  {
      PowerPCCPU *cpu = opaque;
@@ -60,8 +69,6 @@ static void amigaone_init(MachineState *machine)
      PowerPCCPU *cpu;
      CPUPPCState *env;
      MemoryRegion *rom, *pci_mem, *mr;
-    const char *fwname = machine->firmware ?: PROM_FILENAME;
-    char *filename;
      ssize_t sz;
      PCIBus *pci_bus;
      Object *via;
@@ -94,20 +101,24 @@ static void amigaone_init(MachineState *machine)
      }

/* allocate and load firmware */

-    filename = qemu_find_file(QEMU_FILE_TYPE_BIOS, fwname);
-    if (filename) {
-        rom = g_new(MemoryRegion, 1);
-        memory_region_init_rom(rom, NULL, "rom", PROM_SIZE, &error_fatal);
-        memory_region_add_subregion(get_system_memory(), PROM_ADDR, rom);
+    rom = g_new(MemoryRegion, 1);
+    memory_region_init_rom(rom, NULL, "rom", PROM_SIZE, &error_fatal);
+    memory_region_add_subregion(get_system_memory(), PROM_ADDR, rom);
+    if (!machine->firmware) {
+        rom_add_blob_fixed("dummy-fw", dummy_fw, sizeof(dummy_fw),
+                           PROM_ADDR + PROM_SIZE - 0x80);
+    } else {
+        g_autofree char *filename = qemu_find_file(QEMU_FILE_TYPE_BIOS,
+                                                   machine->firmware);
+        if (!filename) {
+            error_report("Could not find firmware '%s'", machine->firmware);
+            exit(1);
+        }
          sz = load_image_targphys(filename, PROM_ADDR, PROM_SIZE);
          if (sz <= 0 || sz > PROM_SIZE) {
              error_report("Could not load firmware '%s'", filename);
              exit(1);
          }
-        g_free(filename);
-    } else if (!qtest_enabled()) {
-        error_report("Could not find firmware '%s'", fwname);
-        exit(1);
      }

/* Articia S */