[the__alchemist]

I have an STM32 rust project I've been working on this week. It talks to an ESP using protobuf/RPC.

I'm doing it bare-metal/no allocator, as I do most embedded projects... and it's flirting with running me out of memory! What do most (and the most popular) protobuf libs do in rust? Use an allocator. What does the ESP itself do? Use an allocator (with FreeRTOS).

Meanwhile I'm using Heapless (Vec and String syntax with a statically-allocated array), on a MCU with 128K flash and 32K Ram... This won't end well.

[charleslmunger]

If you use upb, an allocator is optional - you can provide a presized block to upb_Arena and a NULL upb_alloc. Of course, you'll still fail to parse a message with an in memory representation larger than your region.

[javier2]

Think you need an allocator !