Troubleshooting

You may run into compile or run-time issues due to Slint’s requirements. The following sections track issues we’re aware of and how to solve them.

Rust Compilation Error During Slint Build

You see the following error:

error: the `-Z` flag is only accepted on the nightly channel of Cargo, but this is the `stable` channel

Solution: You need to configure your Rust toolchain to use the esp channel. Either set the RUSTUP_TOOLCHAIN environment variable to the value esp or create a file called rust-toolchain.toml in your project directory with the following contents:

[toolchain]
channel = "esp"

The device crashes at boot or enter a boot loop

One reason could be that you don’t have enough ram for the heap or the stack. Make sure that the stack is big enough (~8KiB), and that all the RAM was made available for the heap allocator.

Wrong colors shown

If colors look inverted on your display, it may be an incompatibility between how RGB565 colors are ordered in little-endian and your display expecting a different byte order. Typically, esp32 devices are little ending and display controllers often expect big-endian or esp_lcd configures them accordingly. Therefore, by default Slint converts pixels to big-endian. If your display controller expects little endian, set the color_swap_16 field in SlintPlatformConfiguration to false.

Errors about multiple symbol definitions when linking

You see errors at application link time such as these:

compiler_builtins.4c2482f45199cb1e-cgu.05:(.text.__udivdi3+0x0): multiple definition of `__udivdi3'; .../libgcc.a(_udivdi3.o): first defined here

Solution: Add -Wl,--allow-multiple-definition to your linker flags by using the following cmake command:

target_link_options(${COMPONENT_LIB} PUBLIC -Wl,--allow-multiple-definition)