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loading UEFI using ovmf_prebuilt=0.2.3 with ovmf_code and ovmf_vars

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v4zha
2025-04-24 16:58:59 +05:30
parent ce01059620
commit 8a1267477a
1 changed files with 16 additions and 8 deletions
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24
blog/content/edition-3/posts/02-booting/index.md
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@@ -1011,27 +1011,35 @@ Now we can create our `qemu-uefi` executable at `src/bin/qemu-uefi.rs`:
```rust ,hl_lines=3-15 ```rust ,hl_lines=3-15
// src/bin/qemu-uefi.rs // src/bin/qemu-uefi.rs
use std::{ use std::{
env, env, process::{self, Command}
process::{self, Command},
}; };
use ovmf_prebuilt::{Arch, FileType, Prebuilt, Source};
fn main() { fn main() {
let prebuilt =
Prebuilt::fetch(Source::LATEST, "target/ovmf").unwrap();
let ovmf_code = prebuilt.get_file(Arch::X64, FileType::Code);
let ovmf_vars = prebuilt.get_file(Arch::X64, FileType::Vars);
let mut qemu = Command::new("qemu-system-x86_64"); let mut qemu = Command::new("qemu-system-x86_64");
qemu.arg("-drive"); qemu.args([
qemu.arg(format!("format=raw,file={}", env!("UEFI_IMAGE"))); "-drive",
qemu.arg("-bios").arg(ovmf_prebuilt::ovmf_pure_efi()); &format!("format=raw,if=pflash,readonly=on,file={}", ovmf_code.to_str().unwrap()),
"-drive",
&format!("format=raw,if=pflash,file={}", ovmf_vars.to_str().unwrap()),
"-drive",
&format!("format=raw,file={}", env!("UEFI_IMAGE")),
]);
let exit_status = qemu.status().unwrap(); let exit_status = qemu.status().unwrap();
process::exit(exit_status.code().unwrap_or(-1)); process::exit(exit_status.code().unwrap_or(-1));
} }
``` ```
It's very similar to our `qemu-bios` executable. It's very similar to our `qemu-bios` executable.
The only two differences are that it passes an additional `-bios` argument and that it uses the `UEFI_IMAGE` instead of the `BIOS_IMAGE`. The only two differences are that it passes two additional `-drive if=pflash,..` arguments to load UEFI firmware (`OVMF_CODE.fd`) and writable NVRAM (`OVMF_VARS.fd`), and that it uses the `UEFI_IMAGE` instead of the `BIOS_IMAGE`.
Using a quick `cargo run --bin qemu-uefi`, we can confirm that it works as intended. Using a quick `cargo run --bin qemu-uefi`, we can confirm that it works as intended.
### Screen Output ### Screen Output
While we see some screen output from the bootloader, our kernel still does nothing. While we see some screen output from the bootloader, our kernel still does nothing.