build: envkernel: build for the correct channel

We currently always build kernel packages for the primary channel, which
will usually be systemd-edge. This will cause sideload to fail since it
correctly only looks in the edge repo.

Update envkernel to get the proper channel name and put the kernel
there, so they will always be in the local edge repo and not the
systemd-edge one.

Signed-off-by: Caleb Connolly <caleb@postmarketos.org>
Part-of: !2572

pmb/build/envkernel.py

@@ -11,6 +11,7 @@ import pmb.aportgen
 import pmb.aportgen.core
 import pmb.build
 import pmb.build.autodetect
+from pmb.core.pkgrepo import pkgrepo_relative_path
 import pmb.chroot
 from pmb.types import Env, PathString, PmbArgs
 import pmb.helpers
@@ -134,13 +135,19 @@ include ../Makefile
 
 
 def run_abuild(
-    context: Context, pkgname: str, arch: Arch, apkbuild_path: Path, kbuild_out: str
+    context: Context,
+    pkgname: str,
+    arch: Arch,
+    pmaports_path: Path,
+    apkbuild_path: Path,
+    kbuild_out: str,
 ) -> None:
     """
     Prepare build environment and run abuild.
 
     :param pkgname: package name of a linux kernel aport
     :param arch: architecture for the kernel
+    :param pmaports_path: path to the aports dir this package is part of
     :param apkbuild_path: path to APKBUILD of the kernel aport
     :param kbuild_out: kernel build system output sub-directory
     """
@@ -174,7 +181,8 @@ def run_abuild(
     # FIXME: duplicated from pmb.build._package.run_aports()
     # This is needed to set up the package output directory for
     # abuild and shouldn't really be done here.
-    channel = pmb.config.pmaports.read_config()["channel"]
+    channel = pmb.config.pmaports.read_config(pmaports_path)["channel"]
+    print(f"Building for channel: {channel}")
     pkgdir = context.config.work / "packages" / channel
     if not pkgdir.exists():
         pmb.helpers.run.root(["mkdir", "-p", pkgdir])
@@ -262,8 +270,10 @@ def package_kernel(args: PmbArgs) -> None:
     message = f"({chroot}) build {output}"
     logging.info(message)
 
+    pmaports_path = pkgrepo_relative_path(aport)[0]
+
     try:
-        run_abuild(context, pkgname, arch, apkbuild_path, kbuild_out)
+        run_abuild(context, pkgname, arch, pmaports_path, apkbuild_path, kbuild_out)
     except Exception as e:
         pmb.helpers.mount.umount_all(Chroot.native() / "mnt/linux")
         raise e