nixos: Get rid of systemConfig kernel parameter

It was introduced in c10fe14 but removed in c4f910f.

It remained such that people with older generations in their boot
entries could still boot those. Given that the parameter hasn't had any
use in quite some years, it seems safe to remove now.

Fixes #60184

nixos/modules/installer/cd-dvd/system-tarball-fuloong2f.nix

@@ -26,7 +26,7 @@ let
   # A clue for the kernel loading
   kernelParams = pkgs.writeText "kernel-params.txt" ''
     Kernel Parameters:
-      init=/boot/init systemConfig=/boot/init ${toString config.boot.kernelParams}
+      init=/boot/init ${toString config.boot.kernelParams}
   '';
 
   # System wide nixpkgs config

nixos/modules/installer/cd-dvd/system-tarball-pc.nix

@@ -23,13 +23,13 @@ let
     label nixos
       MENU LABEL ^NixOS using nfsroot
       KERNEL bzImage
-      append ip=dhcp nfsroot=/home/pcroot systemConfig=${config.system.build.toplevel} init=${config.system.build.toplevel}/init rw
+      append ip=dhcp nfsroot=/home/pcroot init=${config.system.build.toplevel}/init rw
 
     # I don't know how to make this boot with nfsroot (using the initrd)
     label nixos_initrd
       MENU LABEL NixOS booting the poor ^initrd.
       KERNEL bzImage
-      append initrd=initrd ip=dhcp nfsroot=/home/pcroot systemConfig=${config.system.build.toplevel} init=${config.system.build.toplevel}/init rw
+      append initrd=initrd ip=dhcp nfsroot=/home/pcroot init=${config.system.build.toplevel}/init rw
 
     label memtest
       MENU LABEL ^${pkgs.memtest86.name}

nixos/modules/misc/crashdump.nix

@@ -53,7 +53,7 @@ in
         ${pkgs.kexectools}/sbin/kexec -p /run/current-system/kernel \
         --initrd=/run/current-system/initrd \
         --reset-vga --console-vga \
-        --command-line="systemConfig=$(readlink -f /run/current-system) init=$(readlink -f /run/current-system/init) irqpoll maxcpus=1 reset_devices ${kernelParams}"
+        --command-line="init=$(readlink -f /run/current-system/init) irqpoll maxcpus=1 reset_devices ${kernelParams}"
       '';
       kernelParams = [
        "crashkernel=${crashdump.reservedMemory}"

nixos/modules/system/boot/loader/generic-extlinux-compatible/extlinux-conf-builder.sh

@@ -109,7 +109,7 @@ addEntry() {
             exit 1
         fi
     fi
-    echo "  APPEND systemConfig=$path init=$path/init $extraParams"
+    echo "  APPEND init=$path/init $extraParams"
 }
 
 tmpFile="$target/extlinux/extlinux.conf.tmp.$$"

nixos/modules/system/boot/loader/grub/install-grub.pl

@@ -459,7 +459,6 @@ sub addEntry {
     # FIXME: $confName
 
     my $kernelParams =
-        "systemConfig=" . Cwd::abs_path($path) . " " .
         "init=" . Cwd::abs_path("$path/init") . " " .
         readFile("$path/kernel-params");
     my $xenParams = $xen && -e "$path/xen-params" ? readFile("$path/xen-params") : "";

nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py

@@ -101,7 +101,7 @@ def write_entry(profile, generation, machine_id):
         entry_file = "@efiSysMountPoint@/loader/entries/nixos-generation-%d.conf" % (generation)
     generation_dir = os.readlink(system_dir(profile, generation))
     tmp_path = "%s.tmp" % (entry_file)
-    kernel_params = "systemConfig=%s init=%s/init " % (generation_dir, generation_dir)
+    kernel_params = "init=%s/init " % generation_dir
 
     with open("%s/kernel-params" % (generation_dir)) as params_file:
         kernel_params = kernel_params + params_file.read()