The existing load_boot_modules_from_dtb() reader walks
/chosen/multiboot,module nodes — a hand-rolled convention from
bugaevc/wip-aarch64 designed for bare-metal multi-module Hurd
boot via u-boot's `fdt mknod`. No off-the-shelf bootloader
emits it, which is why our test harness has been using QEMU's
-device guest-loader to synthesise it.
Add a fallback for the standard arm64 boot protocol: when no
multiboot,module nodes are found, look for /chosen/linux,initrd-
start + linux,initrd-end + /chosen/bootargs and treat the pair
as a single bootstrap module. Single-module by design — the
standard protocol has only one initrd slot. Production
multi-module boots stay on the multiboot,module path above.
GRUB on arm64-efi emits this form natively when given `linux
<kernel>` + `initrd <module>`, which lets the upstream test
harness drive gnumach on arm64 the same way it drives x86:
grub-mkrescue ISO -> qemu -cdrom test.iso, no per-arch
boot-runner machinery.
The multiboot,module reader has no unit-test coverage on its
own (it lives for bare-metal users with the u-boot setup
documented in aarch64/BOOTING); the test suite added in
subsequent commits exercises both paths — the initrd path
through every per-test ISO run, and the multiboot,module path
through a dedicated test that boots via guest-loader.
---
aarch64/aarch64/model_dep.c | 50 +++++++++++++++++++++++++++++++++++++
1 file changed, 50 insertions(+)
diff --git a/aarch64/aarch64/model_dep.c b/aarch64/aarch64/model_dep.c
index 9c09c052..b1f1611c 100644
--- a/aarch64/aarch64/model_dep.c
+++ b/aarch64/aarch64/model_dep.c
@@ -444,6 +444,56 @@ static __attribute__((noinline)) void
load_boot_modules_from_dtb(void)
i++;
}
+ /*
+ * Fall back to the standard arm64 boot protocol's initrd if no
+ * multiboot,module nodes were found. GRUB on arm64-efi, and any
+ * stock arm bootloader using the linux command, emits the initial
+ * ramdisk via /chosen/linux,initrd-start + linux,initrd-end and
+ * the kernel command line via /chosen/bootargs. Treat that pair
+ * as a single bootstrap module so test harnesses (and anyone who
+ * doesn't want to hand-roll the multiboot,module nodes per
+ * aarch64/BOOTING) can drive gnumach through unmodified GRUB.
+ *
+ * Single-module by design — the standard protocol has only one
+ * initrd slot. Production multi-module boots use the
+ * multiboot,module path above.
+ */
+ if (i == 0) {
+ struct dtb_prop start_prop, end_prop, bootargs_prop;
+
+ start_prop = dtb_node_find_prop(&chosen, "linux,initrd-start");
+ end_prop = dtb_node_find_prop(&chosen, "linux,initrd-end");
+ bootargs_prop = dtb_node_find_prop(&chosen, "bootargs");
+
+ if (!DTB_IS_SENTINEL(start_prop) &&
+ !DTB_IS_SENTINEL(end_prop) &&
+ !DTB_IS_SENTINEL(bootargs_prop)) {
+ vm_offset_t off1 = 0, off2 = 0;
+ uint64_t initrd_start, initrd_end;
+
+ initrd_start = dtb_prop_read_cells(&start_prop,
+ start_prop.length /
4,
+ &off1);
+ initrd_end = dtb_prop_read_cells(&end_prop,
+ end_prop.length / 4,
+ &off2);
+
+ printf("module 0 (initrd): %s\n",
+ (const char *) bootargs_prop.data);
+ boot_modules[0].string = kvtophys((vm_offset_t)
+ bootargs_prop.data);
+ boot_modules[0].mod_start = initrd_start;
+ boot_modules[0].mod_end = initrd_end;
+ boot_modules[0].reserved = 0;
+
+ pmap_reserve_phys_range(
+ round_page(boot_modules[0].mod_start),
+ round_page(boot_modules[0].mod_end));
+
+ i = 1;
+ }
+ }
+
if (i == 0)
panic("No bootstrap modules loaded with Mach\n");
--
2.54.0
