Remove bootimage version placeholders

Author: 64

README.md

@@ -38,7 +38,7 @@ You need a nightly [Rust](https://www.rust-lang.org) compiler and [cargo xbuild]
 
 ## Build
 
-The simplest way to use the bootloader is in combination with the [bootimage](https://github.com/rust-osdev/bootimage) tool. This crate **requires at least bootimage PLACEHOLDER**. With the tool installed, you can add a normal cargo dependency on the `bootloader` crate to your kernel and then run `bootimage build` to create a bootable disk image. You can also execute `bootimage run` to run your kernel in [QEMU](https://www.qemu.org/) (needs to be installed).
+The simplest way to use the bootloader is in combination with the [bootimage](https://github.com/rust-osdev/bootimage) tool. This crate **requires at least bootimage 0.7.7**. With the tool installed, you can add a normal cargo dependency on the `bootloader` crate to your kernel and then run `bootimage build` to create a bootable disk image. You can also execute `bootimage run` to run your kernel in [QEMU](https://www.qemu.org/) (needs to be installed).
 
 To compile the bootloader manually, you need to invoke `cargo xbuild` with two environment variables:
 * `KERNEL`: points to your kernel executable (in the ELF format)

azure-pipelines.yml

@@ -96,7 +96,9 @@ steps:
 
 - script: cargo xbuild --bin bootloader --features binary --release
   displayName: 'Build Bootloader'
-  env: { KERNEL: "test-kernel/target/x86_64-test-kernel/debug/test-kernel" }
+  env:
+    KERNEL: "test-kernel/target/x86_64-test-kernel/debug/test-kernel"
+    KERNEL_MANIFEST: "test-kernel/Cargo.toml"
 
 - script: cargo objcopy -- -I elf64-x86-64 -O binary --binary-architecture=i386:x86-64 target/x86_64-bootloader/release/bootloader target/x86_64-bootloader/release/bootloader.bin
   displayName: 'Convert Bootloader ELF to Binary'

build.rs

@@ -239,7 +239,7 @@ fn main() {
     match env::var("KERNEL_MANIFEST") {
         Err(env::VarError::NotPresent) => {
             panic!("The KERNEL_MANIFEST environment variable must be set for building the bootloader.\n\n\
-                 If you use `bootimage` for building you need at least version PLACEHOLDER. You can \
+                 If you use `bootimage` for building you need at least version 0.7.7. You can \
                  update `bootimage` by running `cargo install bootimage --force`.");
         }
         Err(env::VarError::NotUnicode(_)) => {