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Add new required target-c-int-width field to target json (#354)

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Philipp Oppermann
2017-10-03 13:11:22 +02:00
committed by GitHub
parent 0175e83387
commit 82c4a6f0a0
3 changed files with 6 additions and 1 deletions
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blog/content/posts/03-set-up-rust/index.md
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@@ -98,6 +98,7 @@ Rust allows us to define [custom targets] through a JSON configuration file. A m
"linker-flavor": "gcc",
"target-endian": "little",
"target-pointer-width": "64",
"target-c-int-width": "32",
"arch": "x86_64",
"os": "linux"
}
@@ -132,6 +133,7 @@ For our target system, we define the following JSON configuration in a file name
"linker-flavor": "gcc",
"target-endian": "little",
"target-pointer-width": "64",
"target-c-int-width": "32",
"arch": "x86_64",
"os": "none",
"disable-redzone": true,
@@ -139,7 +141,7 @@ For our target system, we define the following JSON configuration in a file name
}
```
As `llvm-target` we use `x86_64-unknown-none`, which defines the `x86_64` architecture, an `unknown` vendor, and no operating system (`none`). The ABI doesn't matter for us, so we just leave it off. The `data-layout` field is just copied from the `x86_64-unknown-linux-gnu` target. We also use the same values for the `target-endian`, `target-pointer-width`, and `arch` fields. For the `os` field we choose `none`, since our kernel runs on bare metal.
As `llvm-target` we use `x86_64-unknown-none`, which defines the `x86_64` architecture, an `unknown` vendor, and no operating system (`none`). The ABI doesn't matter for us, so we just leave it off. The `data-layout` field is just copied from the `x86_64-unknown-linux-gnu` target. We also use the same values for the `target-endian`, `target-pointer-width`, `target-c-int-width`, and `arch` fields. For the `os` field we choose `none`, since our kernel runs on bare metal.
#### The Red Zone
The [red zone] is an optimization of the [System V ABI] that allows functions to temporary use the 128 bytes below its stack frame without adjusting the stack pointer: