Re: [PATCH 1/2] host/rootfs: use initramfs in "make run"

["José Pekkarinen" <jose.pekkarinen@unikie.com>]

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On Thu, Sep 1, 2022 at 1:47 PM Alyssa Ross <hi@alyssa.is> wrote:

> This will allow us to stop compiling e.g. the virtio-blk module into
> the kernel, because it will be loaded by the initramfs.
>
> This introduces some duplication between the rootfs and initramfs's
> Makefiles.  I don't think it's worth the effort at the moment to try
> to reduce that, because it would come at the expense of additional
> complexity in the Makefiles.  We can revisit this later if we want to.
>
> Signed-off-by: Alyssa Ross <hi@alyssa.is>
>

Tested-by: José Pekkarinen <jose.pekkarinen@unikie.com>


> ---
>  host/rootfs/Makefile  | 32 ++++++++++++++++++++++++++++----
>  host/rootfs/shell.nix | 10 ++++++++--
>  2 files changed, 36 insertions(+), 6 deletions(-)
>
> diff --git a/host/rootfs/Makefile b/host/rootfs/Makefile
> index 41cf87c..31f76d2 100644
> --- a/host/rootfs/Makefile
> +++ b/host/rootfs/Makefile
> @@ -6,6 +6,9 @@
>  # QEMU_KVM = qemu-system-x86_64 -enable-kvm.
>  QEMU_KVM = qemu-kvm
>
> +SCRIPTS = ../../scripts
> +VERITYSETUP = veritysetup
> +
>  # tar2ext4 will leave half a filesystem behind if it's interrupted
>  # half way through.
>  build/rootfs.ext4: build/rootfs.tar
> @@ -116,16 +119,37 @@ clean:
>         rm -rf build
>  .PHONY: clean
>
> -run: build/rootfs.ext4 $(EXT_FS)
> +# veritysetup format produces two files, but Make only (portably)
> +# supports one output per rule, so we combine the two outputs then
> +# define two more rules to separate them again.
> +build/rootfs.verity: build/rootfs.ext4
> +       $(VERITYSETUP) format build/rootfs.ext4
> build/rootfs.verity.superblock.tmp \
> +           | awk -F ':[[:blank:]]*' '$$1 == "Root hash" {print $$2;
> exit}' \
> +           > build/rootfs.verity.roothash.tmp
> +       cat build/rootfs.verity.roothash.tmp
> build/rootfs.verity.superblock.tmp \
> +           > $@
> +       rm build/rootfs.verity.roothash.tmp
> build/rootfs.verity.superblock.tmp
> +build/rootfs.verity.roothash: build/rootfs.verity
> +       head -n 1 build/rootfs.verity > $@
> +build/rootfs.verity.superblock: build/rootfs.verity
> +       tail -n +2 build/rootfs.verity > $@
> +
> +build/live.img: $(SCRIPTS)/format-uuid.sh $(SCRIPTS)/make-gpt.sh
> build/rootfs.verity.superblock build/rootfs.verity.roothash
> build/rootfs.ext4
> +       $(SCRIPTS)/make-gpt.sh $@.tmp \
> +
>  build/rootfs.verity.superblock:2c7357ed-ebd2-46d9-aec1-23d437ec2bf5:$$($(SCRIPTS)/format-uuid.sh
> "$$(dd if=build/rootfs.verity.roothash bs=32 skip=1 count=1 status=none)") \
> +
>  build/rootfs.ext4:4f68bce3-e8cd-4db1-96e7-fbcaf984b709:$$($(SCRIPTS)/format-uuid.sh
> "$$(head -c 32 build/rootfs.verity.roothash)")
> +       mv $@.tmp $@
> +
> +run: build/live.img $(EXT_FS) build/rootfs.verity.roothash
>         $(QEMU_KVM) -cpu host -m 2G \
> -           -machine q35,kernel=$(KERNEL),kernel-irqchip=split \
> +           -machine
> q35,kernel=$(KERNEL),kernel-irqchip=split,initrd=$(INITRAMFS) \
>             -display gtk,gl=on \
>             -qmp unix:vmm.sock,server,nowait \
>             -monitor vc \
>             -parallel none \
> -           -drive file=build/rootfs.ext4,if=virtio,format=raw,readonly=on
> \
> +           -drive file=build/live.img,if=virtio,format=raw,readonly=on \
>             -drive file=$(EXT_FS),if=virtio,format=raw,readonly=on \
> -           -append "console=ttyS0 root=/dev/vda ext=/dev/vdb
> intel_iommu=on" \
> +           -append "console=ttyS0 roothash=$$(<
> build/rootfs.verity.roothash) ext=/dev/vdb intel_iommu=on" \
>             -device intel-iommu,intremap=on \
>             -device virtio-vga-gl \
>             -device vhost-vsock-pci,guest-cid=3
> diff --git a/host/rootfs/shell.nix b/host/rootfs/shell.nix
> index 3b2310f..fe9df1b 100644
> --- a/host/rootfs/shell.nix
> +++ b/host/rootfs/shell.nix
> @@ -1,18 +1,24 @@
>  # SPDX-License-Identifier: MIT
>  # SPDX-FileCopyrightText: 2021 Alyssa Ross <hi@alyssa.is>
> +# SPDX-FileCopyrightText: 2022 Unikie
>
>  { pkgs ? import <nixpkgs> {} }:
>
> +let
> +  rootfs = import ./. { inherit pkgs; };
> +in
> +
>  with pkgs;
>
> -(import ./. { inherit pkgs; }).overrideAttrs (
> +rootfs.overrideAttrs (
>  { passthru ? {}, nativeBuildInputs ? [], ... }:
>
>  {
>    nativeBuildInputs = nativeBuildInputs ++ [
> -    jq netcat qemu_kvm reuse util-linux
> +    cryptsetup jq netcat qemu_kvm reuse util-linux
>    ];
>
>    EXT_FS = pkgsStatic.callPackage ../initramfs/extfs.nix { inherit pkgs;
> };
> +  INITRAMFS = import ../initramfs { inherit pkgs rootfs; };
>    KERNEL =
> "${passthru.kernel}/${stdenv.hostPlatform.linux-kernel.target}";
>  })
> --
> 2.37.1
>
>

-- 

José.

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