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fixed repeated "the" typo (#691)

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MarinPostma
2019-11-23 15:41:31 +01:00
committed by Philipp Oppermann
parent 555b5aece1
commit 6d95caec31
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blog/content/second-edition/posts/04-testing/index.md
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@@ -199,7 +199,7 @@ pub fn exit_qemu(exit_code: QemuExitCode) {
} }
``` ```
The function creates a new [`Port`] at `0xf4`, which is the `iobase` of the `isa-debug-exit` device. Then it writes the the passed exit code to the port. We use `u32` because we specified the `iosize` of the `isa-debug-exit` device as 4 bytes. Both operations are unsafe, because writing to an I/O port can generally result in arbitrary behavior. The function creates a new [`Port`] at `0xf4`, which is the `iobase` of the `isa-debug-exit` device. Then it writes the passed exit code to the port. We use `u32` because we specified the `iosize` of the `isa-debug-exit` device as 4 bytes. Both operations are unsafe, because writing to an I/O port can generally result in arbitrary behavior.
For specifying the exit status, we create a `QemuExitCode` enum. The idea is to exit with the success exit code if all tests succeeded and with the failure exit code otherwise. The enum is marked as `#[repr(u32)]` to represent each variant by an `u32` integer. We use exit code `0x10` for success and `0x11` for failure. The actual exit codes do not matter much, as long as they don't clash with the default exit codes of QEMU. For example, using exit code `0` for success is not a good idea because it becomes `(0 << 1) | 1 = 1` after the transformation, which is the default exit code when QEMU failed to run. So we could not differentiate a QEMU error from a successful test run. For specifying the exit status, we create a `QemuExitCode` enum. The idea is to exit with the success exit code if all tests succeeded and with the failure exit code otherwise. The enum is marked as `#[repr(u32)]` to represent each variant by an `u32` integer. We use exit code `0x10` for success and `0x11` for failure. The actual exit codes do not matter much, as long as they don't clash with the default exit codes of QEMU. For example, using exit code `0` for success is not a good idea because it becomes `(0 << 1) | 1 = 1` after the transformation, which is the default exit code when QEMU failed to run. So we could not differentiate a QEMU error from a successful test run.