This is a bootloader for CKB-VM programs, which enables the following behavior:
- Stack is moved from 0 - 512KB region
- Code starts from 512KB upwards
Assuming a program then leverages heap memory starting at _end and upwards, there will be no chance of overlapping between stack and heap. This enables us to use as much heap memory as possible, while also keeping program safe.
To use this bootloader, include bootloader.S in our program, then also use ld_interface.ld as the linker script. An example making those changes to a CKB-VM program, can be found here.
Note that the default provided file is configured to use a stack of 512KB. For certain programs, this might not be enough(e.g., ckb-auth requires a big stack to hold secp256k1 precomputed tables). You can use the following commands to build bootloader with a bigger stack, for example, 2MB:
./regenerate 0x200000
After the command finishes, bootloader.S and ld_interface.ld will be updated accordingly, feel free to then copy those 2 files to your project to setup a bigger stack.
For now, this library is only tested against the following environment:
rust-lldorlldfrom LLVM used as the final linker- CKB-VM script version 1 or above is used