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bf6e5a0fef
Move the `test-spawn` program into `services` and document it better. Signed-off-by: Sean Cross <sean@xobs.io>
31 lines
No EOL
1.5 KiB
Markdown
31 lines
No EOL
1.5 KiB
Markdown
# Spawn a process
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This crate represents an initial program that will run when a process
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starts up. It will listen on a Server and take orders from the parent
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process to finish setting itself up.
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## Initialization
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The process starts with a stack and a text section but no heap, BSS,
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or data section. The entrypoint looks like this:
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```rust
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pub extern "C" init(a1: u32, a2: u32, a3: u32, a4: u32) -> ! {
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let sid = xous::SID::from_u32(a1, a2, a3, a4);
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loop {}
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}
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```
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This process is responsible for performing its own bootstrapping (i.e. allocating/initializing
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.data and .bss), after which it should accept messages on the connection and copy data as necessary.
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## API
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The following messages are supported:
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| Mnemonic | Opcode | Type | Description |
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| ---------------- | ------ | ---- | -------------------------------------------------------------------------------------------------------- |
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| WriteMemory | 1 | M | Write memory into an area of memory. The `Offset` field is used to determine where the block will start. |
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| WriteArgs | 2 | M | Reserved |
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| WriteEnvironment | 3 | M | Reserved |
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| FinishSetup | 255 | * | Terminate the loop, shutdown the server, and start the program. | |