pongoOS for QEMU

Fork of PongoOS which can be run in QEMU. Working so far:

• Framebuffer (ramfb)
• UART/serial (pl011)
• Interrupt Controller (GICv2)
• Device tree parsing
• QEMU fw_cfg parsing

Not working:

• Everything else

It can be run both virtualized using Hypervisor.framework on M1 or emulated with TCG. Although only the latter supports gdb debugging.

You need to use the utmapp fork of qemu which has HVF support and working TCG emulation. Apply the following patch to change the memory layout to what pongo expects:

diff --git a/hw/arm/virt.c b/hw/arm/virt.c
index 27dbeb549e..8a208badcb 100644
--- a/hw/arm/virt.c
+++ b/hw/arm/virt.c
@@ -160,7 +160,7 @@ static const MemMapEntry base_memmap[] = {
     [VIRT_PCIE_PIO] =           { 0x3eff0000, 0x00010000 },
     [VIRT_PCIE_ECAM] =          { 0x3f000000, 0x01000000 },
     /* Actual RAM size depends on initial RAM and device memory settings */
-    [VIRT_MEM] =                { GiB, LEGACY_RAMLIMIT_BYTES },
+    [VIRT_MEM] =                { 0x800000000, LEGACY_RAMLIMIT_BYTES },
 };

 /*

Run with Hypervisor.framework

qemu-system-aarch64 \
   -cpu host -M virt,highmem=off -accel hvf \
   -device loader,file=build/Pongo.bin,addr=0x1000,force-raw=on   \
   -device loader,addr=0x1000,cpu-num=0 -m 4096 \
   -device ramfb \
   -serial stdio

Run emulated

qemu-system-aarch64 \
    -cpu cortex-a72 -M virt -accel tcg \
    -device loader,file=build/Pongo.bin,addr=0x1000,force-raw=on \
    -device loader,addr=0x1000,cpu-num=0 -m 4096 \
    -device ramfb \
    -serial stdio

Using qemu's -s -S arguments, you can attach gdb and step through the execution.