m/n/b/mkpayload: support multiple initramfs files
Linux supports multiple concatinated initramfs files and requires using
multiple to provide certain data like microcode for the early loader.
This allows building such payloads with mkpayload.
Change-Id: Ie7ee7886bbfe481d7b723e0476a26ee26425a0b6
Reviewed-on: https://review.monogon.dev/c/monogon/+/548
Reviewed-by: Mateusz Zalega <mateusz@monogon.tech>
diff --git a/metropolis/node/build/efi.bzl b/metropolis/node/build/efi.bzl
index f9d0f44..5f6bfd6 100644
--- a/metropolis/node/build/efi.bzl
+++ b/metropolis/node/build/efi.bzl
@@ -10,7 +10,6 @@
# Find the dependency paths to be passed to mkpayload.
deps = {
"linux": ctx.file.kernel,
- "initrd": ctx.file.initramfs,
"osrel": ctx.file.os_release,
"splash": ctx.file.splash,
"stub": ctx.file.stub,
@@ -39,6 +38,10 @@
args.append("-{}={}".format(name, file.path))
inputs.append(file)
+ for file in ctx.files.initrd:
+ args.append("-initrd={}".format(file.path))
+ inputs.append(file)
+
# Append the output parameter separately, as it doesn't belong with the
# runtime inputs.
image = ctx.actions.declare_file(ctx.attr.name + ".efi")
@@ -73,9 +76,27 @@
"cmdline": attr.string(
doc = "The kernel commandline to be embedded.",
),
- "initramfs": attr.label(
- doc = "The initramfs to be embedded.",
- allow_single_file = True,
+ "initrd": attr.label_list(
+ doc = """
+ List of payloads to concatenate and supply as the initrd parameter to Linux when it boots.
+ The name stems from the time Linux booted from an initial ram disk (initrd), but it's now
+ a catch-all for a bunch of different larger payload for early Linux initialization.
+
+ In Linux 5.15 this can first contain an arbitrary amount of uncompressed cpio archives
+ with directories being optional which is accessed by earlycpio. This is used for both
+ early microcode loading and ACPI table overrides. This can then be followed by an arbitrary
+ amount of compressed cpio archives (even with different compression methods) which will
+ together make up the initramfs. The initramfs is only booted into if it contains either
+ /init or whatever file is specified as init= in cmdline. Technically depending on kernel
+ flags you might be able to supply an actual initrd, i.e. an image of a disk loaded into
+ RAM, but that has been deprecated for nearly 2 decades and should really not be used.
+
+ For kernels designed to run on physical machines this should at least contain microcode,
+ optionally followed by a compressed initramfs. For kernels only used in virtualized
+ setups the microcode can be left out and if no initramfs is needed this option can
+ be omitted completely.
+ """,
+ allow_files = True,
),
"os_release": attr.label(
doc = """