Merge pull request #1410 from v4zha/edition-3

loading UEFI using ovmf_prebuilt=0.2.3 with ovmf_code and ovmf_vars

blog/content/edition-3/posts/02-booting/index.md

@@ -75,7 +75,7 @@ This structure has the following general format:
 | 446    | partition entry 1 | 16   |
 | 462    | partition entry 2 | 16   |
 | 478    | partition entry 3 | 16   |
-| 444    | partition entry 4 | 16   |
+| 494    | partition entry 4 | 16   |
 | 510    | boot signature    | 2    |
 
 The bootstrap code is commonly called the _bootloader_ and responsible for loading and starting the operating system kernel.
@@ -706,7 +706,7 @@ We then use the the `create_uefi_image` and `create_bios_image` methods to creat
 [requires build scripts]: https://doc.rust-lang.org/cargo/reference/build-scripts.html#outputs-of-the-build-script
 [`join`]: https://doc.rust-lang.org/std/path/struct.PathBuf.html#method.join
 
-We can now use use a simple `cargo build` to cross-compile our kernel, build the bootloader, and combine them to create a bootable disk image:
+We can now use a simple `cargo build` to cross-compile our kernel, build the bootloader, and combine them to create a bootable disk image:
 
 ```
 ❯ cargo build
@@ -1011,27 +1011,35 @@ Now we can create our `qemu-uefi` executable at `src/bin/qemu-uefi.rs`:
 
 ```rust ,hl_lines=3-15
 // src/bin/qemu-uefi.rs
-
 use std::{
-    env,
+    env, process::{self, Command}
-    process::{self, Command},
 };
 
+use ovmf_prebuilt::{Arch, FileType, Prebuilt, Source};
+
 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");
-    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.display()),
+        "-drive",
+        &format!("format=raw,if=pflash,file={}", ovmf_vars.display()),
+        "-drive",
+        &format!("format=raw,file={}", env!("UEFI_IMAGE")),
+    ]);
     let exit_status = qemu.status().unwrap();
     process::exit(exit_status.code().unwrap_or(-1));
 }
 ```
 
 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.
 
-
 ### Screen Output
 
 While we see some screen output from the bootloader, our kernel still does nothing.

blog/content/edition-3/posts/03-screen-output/index.md

@@ -149,8 +149,6 @@ In the new module, we create basic structs for representing pixel positions and
 ```rust ,hl_lines=3-16
 // in new kernel/src/framebuffer.rs file
 
-use bootloader_api::info::FrameBuffer;
-
 #[derive(Debug, Clone, Copy, PartialEq, Eq)]
 pub struct Position {
     pub x: usize,
@@ -180,7 +178,7 @@ Next, we create a function for setting a specific pixel in the framebuffer to a
 ```rust ,hl_lines=3 5-39
 // in new kernel/src/framebuffer.rs file
 
-use bootloader_api::info::PixelFormat;
+use bootloader_api::info::{FrameBuffer, PixelFormat};
 
 pub fn set_pixel_in(framebuffer: &mut FrameBuffer, position: Position, color: Color) {
     let info = framebuffer.info();