Combine initrd and squashfs and unified boot

- one one initrd which also includes squashfs
- same procedure for EFI and non-EFI

embed.ipxe

@@ -12,7 +12,7 @@ imgtrust --permanent
 # For the "focal" part of the URL string, in case that changes in the future.
 set ubuntu-variant focal
 
-goto get_platform
+goto get_arch
 
 
 #################
@@ -135,24 +135,6 @@ sleep 5
 exit
 
 
-# set variables based on whether it's EFI or not
-:get_platform
-iseq ${platform} efi && goto is_efi || goto not_efi
-
-# Attributes for EFI boot
-:is_efi
-# hack, see https://github.com/coreos/fedora-coreos-tracker/issues/390#issuecomment-588328137
-set squashfs squashfs.cpio
-set extra_initrd initrd=squashfs.cpio
-goto get_arch
-
-# this sets different attributes for non-EFI (legacy PC) boot
-:not_efi
-set squashfs squashfs
-clear extra_initrd 
-goto get_arch
-
-
 # Get relevant CPU arch.
 :get_arch
 iseq ${buildarch} arm32 && goto start_arm32 ||
@@ -208,9 +190,6 @@ goto static_ip_boot_setup
 # However, note that imgverify will fail if you refer to it as "/squashfs"
 #   instead of "squashfs".
 
-imgfetch http://images.sysdeploy.org/${ubuntu-variant}/${arch-info}/${squashfs} /${squashfs} || goto try_next_card
-imgverify --signer images.sysdeploy.org ${squashfs} http://images.sysdeploy.org/${ubuntu-variant}/${arch-info}/${squashfs}.sig || goto error_handler
-
 # "--signer" validates against the subject common name field of the signing
 #   certificate. That signing cert must have both the digital signature key
 #   usage set and the code-signing key usage extension set.
@@ -219,8 +198,8 @@ imgverify --signer images.sysdeploy.org ${squashfs} http://images.sysdeploy.org/
 #   make sure you pick a common name with a FQDN you control, even if you're
 #   using a custom CA that you import during build.
 
-initrd http://images.sysdeploy.org/${ubuntu-variant}/${arch-info}/boot-initrd || goto try_next_card
+initrd http://images.sysdeploy.org/${ubuntu-variant}/${arch-info}/initrd.cpio || goto try_next_card
-imgverify --signer images.sysdeploy.org boot-initrd http://images.sysdeploy.org/${ubuntu-variant}/${arch-info}/boot-initrd.sig || goto error_handler
+imgverify --signer images.sysdeploy.org boot-initrd http://images.sysdeploy.org/${ubuntu-variant}/${arch-info}/initrd.cpio.sig || goto error_handler
 
 kernel http://images.sysdeploy.org/${ubuntu-variant}/${arch-info}/boot-kernel || goto try_next_card
 imgverify --signer images.sysdeploy.org boot-kernel http://images.sysdeploy.org/${ubuntu-variant}/${arch-info}/boot-kernel.sig || goto error_handler
@@ -233,7 +212,7 @@ echo ip-info ${ip-info}
 
 sleep 1
 
-boot boot-kernel initrd=boot-initrd ${extra_initrd} rootfstype=squashfs root=/squashfs ip=${ip-info} overlayroot=tmpfs:recurse=0 systemd.clock-usec=${unixtime:int32}000000 ds=nocloud-net;s=https://cloud-init.sysdeploy.org/ || goto error_handler
+boot boot-kernel initrd=squashfs.cpio rootfstype=squashfs root=/squashfs ip=${ip-info} overlayroot=tmpfs:recurse=0 systemd.clock-usec=${unixtime:int32}000000 ds=nocloud-net;s=https://cloud-init.sysdeploy.org/ || goto error_handler
 
 # unixtime variable must be used with int32, because that's the only way it
 #   will display as decimal digits. unit32 and string both display as hex.