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<title>Emulating the Badge Under Renode</title>
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<a class="url" href="https://p.xobs.io/c23/">p.xobs.io/fa23</a>
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<section>
<h2>Emulating the Badge Under Renode</h2>
<h3>(Eventually)</h3>
<br />
<h3>Sean "xobs" Cross</h3>
</section>
<section>
<h2>About Me</h2>
<img data-src="img/xobs-projects.jpg">
</section>
<section>
<h2>Talk Outline</h2>
<ol>
<li>What is Renode?</li>
<li>How is it extensible?</li>
<li>What is the state of the badge?</li>
</ol>
</section>
<section>
<section>
<h2>What is Renode?</h2>
</section>
<section>
<h2>Whole-system Emulator</h2>
<ul>
<li>CPU cores</li>
<li>Peripherals</li>
<li>Interconnections</li>
</ul>
</section>
<section>
<h2>Target platforms</h2>
<ul>
<li>Windows</li>
<li>Mac</li>
<li>Linux</li>
<li>
<ul>
<li>CI</li>
</ul>
</li>
</ul>
</section>
<section>
<h2>CPU Cores</h2>
<ul>
<li>x86</li>
<li>arm</li>
<li>arm64</li>
<li>ppc</li>
<li>riscv</li>
<li>spark</li>
<li>xtensa</li>
</ul>
</section>
<section>
<h2>Peripherals</h2>
<img data-src="img/esp32s3-peripheral-list.png">
</section>
<section>
<h2>Peripherals Are Just Special Memory</h2>
<ul>
<li>Writing to a memory address does a thing</li>
<li>Reading from an address gets a result</li>
<li>Interrupts are just GPIOs</li>
</ul>
</section>
<section>
<h2>10% of the Functionality Gets You 90% of the Way There</h2>
<ul>
<li>E.g. in a serial device, baudrate, timers, and parity/stop can be ignored</li>
<li>Just "Tx", "Rx", and interrupt setup</li>
<li>Most software works just fine if you return zeroes for invalid addresses</li>
</ul>
</section>
<section>
<h2>SVD files are your friend</h2>
<ul>
<li>Your chip probably comes with a SVD file</li>
<li>This gives a map of RAM and peripherals</li>
<li>Renode can parse this and use it for logging / defaults</li>
</ul>
</section>
<section>
<h2>Existing Peripherals in Renode</h2>
<ul>
<li>Built-in peripherals for a number of devices</li>
<ul>
<li>STM32</li>
<li>NRF52</li>
<li>IMXRT</li>
<li>LiteX</li>
</ul>
<li>See
https://github.com/renode/renode-infrastructure/tree/master/src/Emulator/Peripherals/Peripherals
for more</li>
</ul>
</section>
<section>
<h2>Creating Peripherals</h2>
<ul>
<li>Renode is written in C#</li>
<li>Like Java, C# has an `eval()` function</li>
<li>Peripherals can be written and loaded at runtime</li>
</ul>
</section>
<section>
<h2>Networks in Renode</h2>
<ul>
<li>Built-in support for CAN, Ethernet, and Wireless</li>
<li>Also possible to add networks at runtime</li>
<li>No latency, just packets of data</li>
<ul>
<li>Different devices run at different speeds</li>
</ul>
</ul>
</section>
<section>
<h2>Other Goodies</h2>
<ul>
<li>LCD monitor with touchscreen support</li>
<li>Python interpreter for quick hacks</li>
<li>Attach GDB to any CPU core</li>
<li>Attach a serial port to a network connection</li>
<li>Scriptable with Robot framework</li>
<li>Log function calls</li>
</ul>
</section>
<section>
<h2>Shortcomings</h2>
<ul>
<li>Unable to unload modules</li>
<ul>
<li>Need to restart Renode when you change a file</li>
</ul>
<li>No real audio support</li>
<ul>
<li>Support for verifying I2S, but can't play it</li>
</ul>
<li>Only x64 hosts</li>
<ul>
<li>Runs under Rosetta on Mac</li>
</ul>
<li>Documentation needs work</li>
<ul>
<li>Use the source!</li>
</ul>
</ul>
</section>
</section>
<section>
<section>
<h2>Extending Renode</h2>
</section>
<section>
<h2>First, Betrusted</h2>
<ul>
<li>FPGA with VexRiscv</li>
<li>2nd FPGA with smaller VexRiscv</li>
<li>16-bit COM bus between them</li>
<li>AES extensions</li>
<li>x25519 "ENGINE" accelerator</li>
<li>SHA accelerator</li>
<li>Battery charger and manager</li>
<li>Custom lcd, timers, and USB</li>
</ul>
</section>
<section>
<h2>Emulating it under Renode</h2>
<ul>
<li>Good enough to develop the OS!</li>
<li>Good enough to catch bugs</li>
</ul>
</section>
<section>
<h2>ENGINE bug</h2>
<ol>
<li>Added test vectors to the OS</li>
<li>Ran test vectors on physical device</li>
<li>Got test vectors passing in Renode</li>
<li>
<ul>
<li>Yay!</li>
</ul>
</li>
<li>Someone (without a device!) decided to add more vectors</li>
<li>Tested in Renode</li>
<li>Passed</li>
<li>Failed on hardware</li>
<li>Bug in detecting overflow condition for normalization in hardware</li>
<li>https://github.com/betrusted-io/gateware/commit/817e284a3d92037b8cb0686735578d2bb60853e9
</li>
</ol>
</section>
<section>
<h2>Getting Started with Renode</h2>
<ol>
<li>Renode Platform Definition (<code>.repl</code>)</li>
<li>Renode Script (<code>.resc</code>)</li>
</ol>
</section>
<section>
<h2>Example project repl</h2>
</section>
<section>
<h2>Example project resc</h2>
</section>
<section>
<h2>Running it</h2>
</section>
<section>
<h2>How to Extend Renode</h2>
<ol>
<li>Find a peripheral that does what you want</li>
<li>
<ul>
<li>You might even find a compatible peripheral!</li>
</ul>
</li>
<li>Copy it to your project</li>
<li>Change the constructor</li>
<li>Change the register set</li>
<li>Import the `.cs` file into Renode</li>
<li>Add it to your platform file</li>
</ol>
</section>
</section>
<section>
<section>
<h1>Demonstration!</h1>
</section>
</section>
<section>
<section>
<h2>Running Badge Software in Renode</h2>
</section>
<section>
<h2>It Doesn't</h2>
</section>
<section>
<h2>Xtensa is an Uncommon Architecture</h2>
<ul>
<li>Audio DSPs</li>
<li>Possibly Intel?</li>
<li>NXP</li>
</ul>
</section>
<section>
<h2>Extensive use of Boot ROM</h2>
<ul>
<img data-src="img/memory-maps.png">
</ul>
</section>
<section>
<h2>Extensive use of Boot ROM</h2>
<ul>
<pre><code class="wrap">$ esptool.py dump_mem \
0x3ff90000 \
65536 \
irom.bin</code></pre>
</ul>
</section>
<!-- <section>
<ul>
<li>Immediately get output</li>
<li>Breaks immediately</li>
</ul>
</section> -->
<section>
<h2>Add a serial port</h2>
<code><pre>
namespace Antmicro.Renode.Peripherals.UART {
public class ESP32_UART : UARTBase, IDoubleWordPeripheral,
IKnownSize {
private readonly DoubleWordRegisterCollection registers;
public ESP32_UART(Machine machine) : base(machine) {
registers = new DoubleWordRegisterCollection(this,
new Dictionary<long, DoubleWordRegister> {
{0x00, new DoubleWordRegister(this).WithValueField(0,8,
writeCallback: (_, v) => TransmitCharacter((byte)v))}
});
}</code></code>
</section>
<section>
<h2>Add a serial port</h2>
<code><pre>
{0x00, new DoubleWordRegister(this)
.WithValueField(0, 8,
writeCallback: (_, v) => TransmitCharacter((byte)v))}</code></code>
</section>
<section>
<img data-src="img/esp32s3-uart.png">
</section>
<section>
<h2>Load SVD file</h2>
<pre><code>sysbus:
init:
ApplySVD @esp32s3.svd</code></pre>
</section>
<section>
<h2>Load SVD file</h2>
<pre><code style="word-wrap: break-word;">
extmem: Unhandled read from offset 0x64.
extmem: Unhandled write to offset 0x64, value 0x3.
sysbus: Read from an unimplemented register SYSTEM:SYSCLK_CONF
(0x600C0060), returning a value from SVD: 0x1. (3)
sysbus: Read from an unimplemented register SYSTEM:PERIP_CLK_EN0
(0x600C0018), returning a value from SVD: 0xF9C1E06F.
sysbus: Write of value 0xF9C1E06F to an unimplemented register
SYSTEM:PERIP_CLK_EN0 (0x600C0018) generated from SVD.
sysbus: Read from an unimplemented register SYSTEM:PERIP_RST_EN0
(0x600C0020), returning a value from SVD: 0x0.
sysbus: Write of value 0x0 to an unimplemented register SYSTEM:PERIP_RST_EN0
0x600C0020) generated from SVD.
sysbus: Read from an unimplemented register SYSTEM:PERIP_RST_EN0
(0x600C0020), returning a value from SVD: 0x0.
sysbus: Write of value 0x4 to an unimplemented register SYSTEM:PERIP_RST_EN0 (0x600C0020) generated from SVD.
</code></pre>
</section>
<section>
<h2>Add Peripherals</h2>
</section>
<section>
<h2>Slowly Advance</h2>
<img data-src="img/esp32s3-more-boot.png">
</section>
<section>
<h2>GDB with ELF</h2>
<img data-src="img/gdb-with-elf.png">
</section>
<section>
<h2>What's Left?</h2>
<ul>
<li>SPI Controller</li>
<li>Interrupt Controller</li>
</ul>
</section>
</section>
<section>
<h2>Getting involved</h2>
<ul>
<li>Try Renode for your projects!</li>
<li>Add CI tests for your firmware!</li>
<li>Explore binaries for unknown targets!</li>
</ul>
<h2 class="fragment">Thank you</h2>
<h3 class="fragment">Questions?</h3>
</section>
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