[OE-core] [PATCH] wic: add UEFI kernel as UEFI stub

[Paul Barker]

On Sat, 4 Jan 2020, at 20:07, Maxim Uvarov wrote:
> Linux kernel can be compiled as UEFI stub and loaded directly
> with UEFI firmware without grub or other UEFI shell.
> 
> Tested with wic file:
> bootloader  --ptable gpt --timeout=0  --append="rootwait"
> part /boot --source bootimg-efi --sourceparams="loader=kernel" \
>  --ondisk sda  --fstype=vfat --label bootfs \
>   --active --align 1024 --use-uuid
> part / --source rootfs --fstype=ext4 --label rootfs \
>   --align 1024 --exclude-path boot/ --use-label
> The same wic file for armv7, armv8 and x86_64.
> 
> Signed-off-by: Maxim Uvarov <maxim.uvarov at linaro.org>
> ---
>  scripts/lib/wic/plugins/source/bootimg-efi.py | 27 +++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/scripts/lib/wic/plugins/source/bootimg-efi.py 
> b/scripts/lib/wic/plugins/source/bootimg-efi.py
> index 2cfdc10ecd..a39d852f6a 100644
> --- a/scripts/lib/wic/plugins/source/bootimg-efi.py
> +++ b/scripts/lib/wic/plugins/source/bootimg-efi.py
> @@ -13,6 +13,7 @@
>  import logging
>  import os
>  import shutil
> +import re
>  
>  from wic import WicError
>  from wic.engine import get_custom_config
> @@ -204,6 +205,8 @@ class BootimgEFIPlugin(SourcePlugin):
>                  cls.do_configure_grubefi(hdddir, creator, cr_workdir, 
> source_params)
>              elif source_params['loader'] == 'systemd-boot':
>                  cls.do_configure_systemdboot(hdddir, creator, 
> cr_workdir, source_params)
> +            elif source_params['loader'] == 'kernel':
> +                return
>              else:
>                  raise WicError("unrecognized bootimg-efi loader: %s" % 
> source_params['loader'])
>          except KeyError:
> @@ -243,6 +246,7 @@ class BootimgEFIPlugin(SourcePlugin):
>              if source_params['loader'] == 'grub-efi':
>                  shutil.copyfile("%s/hdd/boot/EFI/BOOT/grub.cfg" % 
> cr_workdir,
>                                  "%s/grub.cfg" % cr_workdir)
> +
>                  for mod in [x for x in os.listdir(kernel_dir) if 
> x.startswith("grub-efi-")]:
>                      cp_cmd = "cp %s/%s %s/EFI/BOOT/%s" % (kernel_dir, 
> mod, hdddir, mod[9:])
>                      exec_cmd(cp_cmd, True)
> @@ -252,6 +256,29 @@ class BootimgEFIPlugin(SourcePlugin):
>                  for mod in [x for x in os.listdir(kernel_dir) if 
> x.startswith("systemd-")]:
>                      cp_cmd = "cp %s/%s %s/EFI/BOOT/%s" % (kernel_dir, 
> mod, hdddir, mod[8:])
>                      exec_cmd(cp_cmd, True)
> +            elif source_params['loader'] == 'kernel':

How about "uefi-stub" instead of just "kernel" here so it's more explicit?

> +                kernel = get_bitbake_var("KERNEL_IMAGETYPE")
> +                if not kernel:
> +                    raise WicError("Empty KERNEL_IMAGETYPE %s\n" % 
> target)
> +                target = get_bitbake_var("TARGET_SYS")
> +                if not target:
> +                    raise WicError("Unknown arch (TARGET_SYS) %s\n" % 
> target)
> +
> +                if re.match("x86_64", target):
> +                    kernel_efi_image = "bootx64.efi"
> +                elif re.match('i.86', target):
> +                    kernel_efi_image = "bootia32.efi"
> +                elif re.match('aarch64', target):
> +                    kernel_efi_image = "bootaa64.efi"
> +                elif re.match('arm', target):
> +                    kernel_efi_image = "bootarm.efi"
> +                else:
> +                    raise WicError("kernel efi is incompatible with 
> target %s" % target)

Perhaps call this "UEFI stub kernel" instead of just "kernel efi" to make things clearer.

> +
> +                for mod in [x for x in os.listdir(kernel_dir) if 
> x.startswith(kernel)]:
> +                    cp_cmd = "cp %s/%s %s/EFI/BOOT/%s" % (kernel_dir, 
> mod, hdddir, kernel_efi_image)
> +                    WicError("cp_cmd = %s" % cp_cmd);

What's this WicError created here for?

> +                    exec_cmd(cp_cmd, True)

Wouldn't this result in the destination file being overwritten each time through this loop? I guess you're just copying from the grub-efi implementation above though.

>              else:
>                  raise WicError("unrecognized bootimg-efi loader: %s" %
>                                 source_params['loader'])
> -- 
> 2.17.1

-- 
Paul Barker