[boot] Load programs in boot, not kernel

Remove ELF and initrd loading from the kernel. The bootloader now loads
the initial programs, as it does with the kernel. Other files that were
in the initrd are now on the ESP, and non-program files are just passed
as modules.

scripts/templates/build.ninja.j2

@@ -119,10 +119,6 @@ rule dump
     description = Dumping decompiled $name
     command = objdump -DSC -M intel $in > $out
 
-rule makerd
-    description = Making init ramdisk
-    command = $builddir/native/makerd $in $out
-
 rule makest
     description = Making symbol table
     command = nm $in | ${srcroot}/scripts/build_symbol_table.py $out
@@ -191,15 +187,18 @@ build $builddir/fatroot/jsix.elf : cp $builddir/jsix.elf
 build $builddir/fatroot/efi/boot/bootx64.efi : cp $builddir/boot/boot.efi
     name = bootloader to FAT image
 
-build ${builddir}/symbol_table.dat : makest ${builddir}/jsix.elf
+build $builddir/fatroot/nulldrv.elf : cp $builddir/user/nulldrv.elf
+    name = null driver to FAT image
 
-build $builddir/fatroot/initrd.img : makerd ${srcroot}/assets/initrd.toml | $
-    ${builddir}/native/makerd $
-    ${builddir}/user/nulldrv $
-    ${builddir}/symbol_table.dat
+build $builddir/fatroot/terminal.elf : cp $builddir/user/nulldrv.elf
+    name = terminal driver to FAT image
+
+build ${builddir}/fatroot/symbol_table.dat : makest ${builddir}/jsix.elf
 
 build $builddir/jsix.img : makefat | $
-    $builddir/fatroot/initrd.img $
+    $builddir/fatroot/symbol_table.dat $
+    $builddir/fatroot/nulldrv.elf $
+    $builddir/fatroot/terminal.elf $
     $builddir/fatroot/jsix.elf $
     $builddir/fatroot/efi/boot/bootx64.efi
     name = jsix.img