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Update yield info

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Toby Jaffey 2025-12-10 10:48:01 +00:00
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@ -140,7 +140,6 @@ If the bytecode attempts to execute more instructions than the the passed value
* `UVM32_EVT_END` the program has ended * `UVM32_EVT_END` the program has ended
* `UVM32_EVT_ERR` the program has encountered an error * `UVM32_EVT_ERR` the program has encountered an error
* `UVM32_EVT_YIELD` the program has called `yield()` signifying that it requires more instructions to be executed, but has not crashed/hung
* `UVM32_EVT_SYSCALL` the program requests some IO via the host * `UVM32_EVT_SYSCALL` the program requests some IO via the host
## Internals ## Internals
@ -190,9 +189,9 @@ The [RISC-V SBI](https://github.com/riscv-non-isa/riscv-sbi-doc/blob/master/risc
## syscalls ## syscalls
There are two system syscalls used by uvm32, `halt()` and `yield()`. There are two inbuilt syscalls used by uvm32, `halt()` and `yield()`.
`halt()` tells the host that the program has ended normally. `yield()` tells the host that the program requires more instructions to be executed. These are handled internally to uvm32. `halt()` tells the host that the program has ended normally. `yield()` tells the host that the program requires more instructions to be executed. Halt is handled internally and transitions the VM to `UVM32_STATUS_ENDED`, `yield()` is handled in the VM host like other syscalls.
Syscalls are handled in the host by reading the syscall identifier, then using the provided functions to get arguments and set a return response. Direct access to the VM's memory space is not allowed, to avoid memory corruption issues. Syscalls are handled in the host by reading the syscall identifier, then using the provided functions to get arguments and set a return response. Direct access to the VM's memory space is not allowed, to avoid memory corruption issues.