loader: Add elf and bzimage features

Add feature setting to separate elf and bzImage support,
which will make convenience for VMM to select loader type
based on its needs.

Signed-off-by: Cathy Zhang <cathy.zhang@intel.com>

Author: bjzhjing

.buildkite/pipeline.yml

@@ -34,7 +34,55 @@ steps:
           privileged: true
           image: "rustvmm/dev:v2"
           always-pull: true
-  
+
+  - label: "build-gnu-x86-elf"
+    commands:
+     - cargo build --release --features elf
+    retry:
+      automatic: false
+    agents:
+      platform: x86_64.metal
+    plugins:
+      - docker#v3.0.1:
+          image: "rustvmm/dev:v2"
+          always-pull: true
+
+  - label: "unittests-gnu-x86-elf"
+    commands:
+     - cargo test --features elf
+    retry:
+      automatic: false
+    agents:
+      platform: x86_64.metal
+    plugins:
+      - docker#v3.0.1:
+          privileged: true
+          image: "rustvmm/dev:v2"
+
+  - label: "build-gnu-x86-bzimage"
+    commands:
+     - cargo build --release --features bzimage
+    retry:
+      automatic: false
+    agents:
+      platform: x86_64.metal
+    plugins:
+      - docker#v3.0.1:
+          image: "rustvmm/dev:v2"
+          always-pull: true
+
+  - label: "unittests-gnu-x86-bzimage"
+    commands:
+     - cargo test --features bzimage
+    retry:
+      automatic: false
+    agents:
+      platform: x86_64.metal
+    plugins:
+      - docker#v3.0.1:
+          privileged: true
+          image: "rustvmm/dev:v2"
+
   - label: "clippy-x86"
     commands:
      - cargo clippy --all -- -D warnings

Cargo.toml

@@ -5,6 +5,11 @@ authors = ["Cathy Zhang <cathy.zhang@intel.com>"]
 edition = "2018"
 license = "Apache-2.0 AND BSD-3-Clause"
 
+[features]
+default = ["elf"]
+elf = []
+bzimage = []
+
 [dependencies.vm-memory]
 git = "https://github.com/rust-vmm/vm-memory"
 features = ["backend-mmap"]

src/loader/mod.rs

@@ -131,8 +131,10 @@ pub trait KernelLoader {
         F: Read + Seek;
 }
 
+#[cfg(feature = "elf")]
 pub struct Elf;
 
+#[cfg(feature = "elf")]
 impl KernelLoader for Elf {
     /// Loads a kernel from a vmlinux elf image to a slice
     ///
@@ -240,8 +242,10 @@ impl KernelLoader for Elf {
     }
 }
 
+#[cfg(feature = "bzimage")]
 pub struct BzImage;
 
+#[cfg(feature = "bzimage")]
 impl KernelLoader for BzImage {
     /// Loads a bzImage
     ///
@@ -377,13 +381,15 @@ mod test {
     }
 
     #[allow(non_snake_case)]
+    #[cfg(feature = "bzimage")]
     fn make_bzImage() -> Vec<u8> {
         let mut v = Vec::new();
         v.extend_from_slice(include_bytes!("bzimage"));
         v
     }
 
     // Elf64 image that prints hello world on x86_64.
+    #[cfg(feature = "elf")]
     fn make_elf_bin() -> Vec<u8> {
         let mut v = Vec::new();
         v.extend_from_slice(include_bytes!("test_elf.bin"));
@@ -393,6 +399,7 @@ mod test {
     #[allow(safe_packed_borrows)]
     #[allow(non_snake_case)]
     #[test]
+    #[cfg(feature = "bzimage")]
     fn load_bzImage() {
         let gm = create_guest_mem();
         let image = make_bzImage();
@@ -461,6 +468,7 @@ mod test {
     }
 
     #[test]
+    #[cfg(feature = "elf")]
     fn load_elf() {
         let gm = create_guest_mem();
         let image = make_elf_bin();
@@ -550,6 +558,7 @@ mod test {
         assert_eq!(val, '\0' as u8);
     }
 
+    #[cfg(feature = "elf")]
     #[test]
     fn bad_magic() {
         let gm = create_guest_mem();
@@ -562,6 +571,7 @@ mod test {
         );
     }
 
+    #[cfg(feature = "elf")]
     #[test]
     fn bad_endian() {
         // Only little endian is supported
@@ -575,6 +585,7 @@ mod test {
         );
     }
 
+    #[cfg(feature = "elf")]
     #[test]
     fn bad_phoff() {
         // program header has to be past the end of the elf header