Support composite disks.

This adds a new disk file type next to raw files and qcow images that
represent an indirection to further raw disk files. The disk file
itself is a proto file with references to file paths for other disks to
open and their virtual offsets and lengths.

The intention is to make it easy to assemble a single virtual hard disk
out of several distinct partition files. In the particular case of
Cuttlefish running Android in a VM, this is relevant as the Android
build system distributes partitions as separate raw files. While the
simple solution is to pass each partition as a separate raw disk, some
functionality (like the bootloader) assumes there is a partition table
with multiple distinct partitions on a single disk.

Implementing composite disk support in the VMM bridges this gap through
supporting the general-purpose case of a disk built out of multiple
component files.

If desired, this can be extended to support qcow files to support
unusual configurations like a mixed qcow/raw disk.

Enabled with the "composite-disk" feature.

Bug: b/133432409
Change-Id: I2b0c47d92fab13b5dc0ca5a960c7cfd2b7145b87
Signed-off-by: Cody Schuffelen <schuffelen@google.com>
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/crosvm/+/1667767
Reviewed-by: Daniel Verkamp <dverkamp@chromium.org>
Commit-Queue: Daniel Verkamp <dverkamp@chromium.org>
Tested-by: kokoro <noreply+kokoro@google.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/protos/src/lib.rs b/protos/src/lib.rs
index 3fdbdc0..d73fb03 100644
--- a/protos/src/lib.rs
+++ b/protos/src/lib.rs
@@ -11,3 +11,6 @@ pub mod plugin;
 
 #[cfg(feature = "trunks")]
 pub use generated::trunks;
+
+#[cfg(feature = "composite-disk")]
+pub use generated::cdisk_spec;