Packages Zircon's emulator needs (Include ZBI)

[elliott10]

We know how to run Fuchsia to the graphical interface with emulator FEMU:

fuchsia/prebuilt/third_party/aemu/linux-x64/emulator \
-gpu swiftshader_indirect -fuchsia \
-kernel fuchsia/out/default/multiboot.bin -initrd /tmp/tmp_fuchsia/fuchsia-ssh.zbi -m 8192 -serial stdio \
-vga none -machine q35 -enable-kvm -net none \
-drive file=/tmp/tmp_fuchsia/fvm.blk,format=raw,if=none,id=vdisk -device virtio-blk-pci,drive=vdisk \
-append "kernel.serial=legacy"

Emulator needs a lot of file packages to start up the system: multiboot.bin, fvm.blk, fuchsia-ssh.zbi.
Let's explore how to generate these file packages.
By tracking Fuchsia's compilation, I figured it out.

Multiboot: fuchsia/out/default/multiboot.bin

Multiboot-compatible ELF kernel image. kernel bzImage type file

../../prebuilt/third_party/clang/linux-x64/bin/clang++ -o ./multiboot.bin.debug -Wl,-T,../../zircon/kernel/target/pc/multiboot/multiboot.ld -fuse-ld=lld -Wl,-z,combreloc -Wl,-z,relro -Wl,-z,now -Wl,-z,text -Wl,--pack-dyn-relocs=relr --target=x86_64-fuchsia -mcx16 -march=x86-64 -fcrash-diagnostics-dir=clang-crashreports -fcolor-diagnostics -Wl,--color-diagnostics -Wl,-z,max-page-size=4096 -fdebug-prefix-map=/mnt/SSD/xly/fuchsia/fuchsia/out/default.zircon=. -fdebug-prefix-map=/mnt/SSD/xly/fuchsia/fuchsia/out=.. -fdebug-prefix-map=/mnt/SSD/xly/fuchsia/fuchsia=../.. -no-canonical-prefixes -O2 -g3 -Wl,--icf=all -ffunction-sections -Wl,--gc-sections -fdata-sections -fno-exceptions -fno-rtti -m32 -mregparm=3 -fno-pic -Wl,--no-pie -nostdlib -static -Wl,--no-pie -noprofilelib -fno-sanitize-link-runtime -fno-exceptions -Wl,-Map,./multiboot.map -Wl,--start-group @'./multiboot.rsp'  -Wl,--end-group
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../../prebuilt/third_party/clang/linux-x64/bin/llvm-objcopy --strip-sections  ./multiboot.bin.debug  ./multiboot.bin

Drive file: fvm.blk

fuchsia/out/default/obj/build/images/fvm.blk

host_x64/fvm obj/build/images/fvm.blk create --slice 8388608 --blob obj/build/images/blob.blk --data obj/build/images/data.blk

host_x64/blobfs --depfile --json-output blobs.json --compress obj/build/images/blob.blk create --manifest obj/build/images/blob.manifest
# blob.blk is blob type file, include files in the  blob.manifest

host_x64/minfs --depfile obj/build/images/data.blk create
# data.blk is empty, and it's encrypted data type

Ramdisk initrd: fuchsia-ssh.zbi

A Zircon Boot Image (ZBI) contains the kernel image and a RAM disk for the boot filesystem.

../../prebuilt/third_party/clang/linux-x64/bin/clang++ -o kernel-x64-clang/obj/kernel/image -Wl,-T,../../zircon/kernel/image.ld -Wl,--just-symbols,@kernel-x64-clang/gen/kernel/zircon.elf.rsp -fuse-ld=lld -Wl,-z,combreloc -Wl,-z,relro -Wl,-z,now -Wl,-z,text -Wl,--pack-dyn-relocs=relr --target=x86_64-fuchsia -mcx16 -march=x86-64 -fcrash-diagnostics-dir=clang-crashreports -fcolor-diagnostics -Wl,--color-diagnostics -Wl,-z,max-page-size=4096 -fdebug-prefix-map=fuchsia/out/default.zircon=. -fdebug-prefix-map=fuchsia/fuchsia/out=.. -fdebug-prefix-map=fuchsia=../.. -no-canonical-prefixes -O2 -g3 -Wl,--icf=all -fno-exceptions -fno-rtti -nostdlib -static -Wl,--no-pie -noprofilelib -fno-sanitize-link-runtime -fno-exceptions -fdata-sections -ffunction-sections -Wl,--gc-sections -fdata-sections -Wl,--build-id=none -Wl,-defsym,KERNEL_BASE=0xffffffff80100000 -Wl,-defsym,SMP_MAX_CPUS=32 -Wl,-defsym,BOOT_HEADER_SIZE=0x50 -Wl,-Map,kernel-x64-clang/obj/kernel/image.map -Wl,--start-group @'kernel-x64-clang/obj/kernel/image.rsp'  -Wl,--end-group 
# **Kernel** image
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cd out/default.zircon ; ../../prebuilt/third_party/clang/linux-x64/bin/llvm-objcopy -O binary kernel-x64-clang/obj/kernel/image kernel-x64-clang/kernel.zbi
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# kernel.zbi and files in various manifests and some specific files with --entry parameter
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host_x64/zbi --output=fuchsia.zbi --depfile=fuchsia.zbi.d --complete=x64 --compressed=zstd obj/build/images/boot.manifest ../default.zircon/kernel-x64-clang/kernel.zbi obj/src/devices/bin/driver_manager/driver_manager.manifest obj/src/devices/devices.manifest obj/src/power/shutdown-shim/shutdown-shim.manifest obj/src/sys/bootstrap/root_manifests.manifest obj/src/sys/component_manager/component_manager_bootfs.manifest obj/src/security/policy/component_manager_policy.manifest --entry=config/devmgr=obj/build/images/devmgr_config.txt --entry=config/zxcrypt=obj/build/images/zxcrypt_config.txt --type=cmdline --entry=console.shell=true --entry=kernel.enable-debugging-syscalls=true --entry=kernel.enable-serial-syscalls=true --entry=netsvc.all-features=true --entry=netsvc.disable=false --entry=kernel.oom.behavior=reboot --entry=virtcon.hide-on-boot
# fuchsia/out/default/fuchsia.zbi

ZBI package

How to show contents of a zbi package:

host_x64/zbi -t -v input.zbi

How to decompless a zbi package:

host_x64/zbi --extract --output-dir=obj/build/images/fuchsia.zbi/bootfs --json-output=fuchsia.zbi.json fuchsia.zbi
# OR
host_x64/zbi -x -D fuchsia.zbi/bootfs input_fuchsia.zbi

How to merge a zbi package and a folder into a new zbi package:

host_x64/zbi -o output.zbi input.zbi input_dir/