Getting started

[yuppox]

Hi,

I tried building for qemu. What do I need to run one of the samples? What should the command line be? I want to emulate a RPi 3.

[yuppox]

My command line is qemu-system-aarch64.exe -M raspi3b -kernel kernel8-32.img (using sample 41) but QEMU is just a blank window.

[rsta2]

You have to build the sample program for the AArch64 mode (kernel8.img), not for AArch32 (kernel8-32.img), if you want to run it in qemu-system-aarch64.exe. You have to set AARCH=64 in Config.mk before build for that purpose. You need a 64-bit toolchain. Don't forget to clean the whole project using makeall clean from project root and make clean and the sample's directory after changing the configuration in Config.mk.

sample/41-screenanimations is not perfect for a first screen test, because it uses display double buffering by default, which is not supported by QEMU. Please try sample/03-screentext for a first test.

[yuppox]

Thank you. I got it working. It was confusing since the 32-bit build chain worked with the real hardware.

One other question - how can I get my keyboard to work with qemu? So far, I can't get example 08 to work. I'm using the -usb -device usb-kbd option.

When I start qemu, I see this:

00:00:00.55 timer: SpeedFactor is 1.81
00:00:00.56 dwhci: Unknown vendor 0x4F54294A

And nothing happens after that.

[yuppox]

I patched that vendor ID in qemu and that seems to have fixed the problem.

[rsta2]

QEMU normally needs this patch to work with the Circle USB driver and with networking.

[yuppox]

Right, that's what I applied - the second part.

[yuppox]

What I don't understand is that I think a 32-bit build works on real hardware. Why won't it work in qemu?

[yuppox]

Apparently, this is simply a limitation of QEMU. 👎

[rsta2]

There is a version of QEMU (qemu-system-arm), which runs Raspberry Pi 1, 2 and Zero 32-bit binaries.

[yuppox]

Thanks. I tried qemu-system-arm. It doesn't support raspi3b, which is kind of annoying but more importantly, it doesn't support the GPU.

[yuppox]

sample/41-screenanimations is not perfect for a first screen test, because it uses display double buffering by default, which is not supported by QEMU. Please try sample/03-screentext for a first test.

I can't find a good emulator for the Pi. QEMU doesn't seem to support the GPU at all and the framebuffer is not very good (no double buffer, as you noted). It seems like we need a simulator for graphics.

[rsta2]

When you specify a FALSE as third parameter to the constructor of C2DGraphics, you can use it without double-buffering.