Add ATAPI CD-ROM and ISO boot support
* Refactor ATA into per-channel/device model with master/slave
and ATAPI packet command support
* BIOS bootloader: detect CD-ROM sector size, scan full directory
extent. MBR: split reads at 64K DMA boundary.
* Unify partition parsing (GPT then MBR), make devfs and ext2
work on read-only media
* Add ISO and hybrid disk image build scripts, add QEMU UEFI
boot support
* Kernel: iterate disks to find rootfs, init devfs before
publishing disk devices
16 files changed,
802 insertions,
182 deletions