lk2nd: add boot module with extlinux support

Co-authored-by: Stephan Gerhold <[email protected]>

app/aboot/aboot.c

@@ -102,6 +102,9 @@
 #if WITH_LK2ND_DEVICE
 #include <lk2nd/device.h>
 #endif
+#if WITH_LK2ND_BOOT
+#include <lk2nd/boot.h>
+#endif
 
 extern  bool target_use_signed_kernel(void);
 extern void platform_uninit(void);
@@ -4655,6 +4658,9 @@ void cmd_continue(const char *arg, void *data, unsigned sz)
 #if FBCON_DISPLAY_MSG
 		/* Exit keys' detection thread firstly */
 		exit_menu_keys_detection();
+#endif
+#if WITH_LK2ND_BOOT
+		lk2nd_boot();
 #endif
 		boot_linux_from_mmc();
 	}
@@ -5630,6 +5636,11 @@ void aboot_init(const struct app_descriptor *app)
 normal_boot:
 	if (!boot_into_fastboot)
 	{
+#if WITH_LK2ND_BOOT
+		if (!boot_into_recovery)
+			lk2nd_boot();
+#endif
+
 		if (target_is_emmc_boot())
 		{
 			if(!IS_ENABLED(ABOOT_STANDALONE) && emmc_recovery_init())

lk2nd/boot/boot.c

@@ -0,0 +1,74 @@
+// SPDX-License-Identifier: BSD-3-Clause
+/* Copyright (c) 2023 Nikita Travkin <[email protected]> */
+
+#include <debug.h>
+#include <list.h>
+#include <lib/bio.h>
+#include <lib/fs.h>
+#include <stdlib.h>
+#include <target.h>
+
+#include <lk2nd/boot.h>
+#include <lk2nd/hw/bdev.h>
+
+#include "boot.h"
+
+#ifndef LK2ND_BOOT_MIN_SIZE
+#define LK2ND_BOOT_MIN_SIZE (16 * 1024 * 1024)
+#endif
+
+/**
+ * lk2nd_scan_devices() - Scan filesystems and try to boot
+ */
+static void lk2nd_scan_devices(void)
+{
+	struct bdev_struct *bdevs = bio_get_bdevs();
+	char mountpoint[16];
+	bdev_t *bdev;
+	int ret;
+
+	dprintf(INFO, "boot: Trying to boot from the file system...\n");
+
+	list_for_every_entry(&bdevs->list, bdev, bdev_t, node) {
+
+		/* Skip top level block devices. */
+		if (!bdev->is_leaf)
+			continue;
+
+		/* Skip partitions that are too small to have a boot fs on. */
+		if (bdev->size < LK2ND_BOOT_MIN_SIZE)
+			continue;
+
+		snprintf(mountpoint, sizeof(mountpoint), "/%s", bdev->name);
+		ret = fs_mount(mountpoint, "ext2", bdev->name);
+		if (ret < 0)
+			continue;
+
+		if (DEBUGLEVEL >= SPEW) {
+			dprintf(SPEW, "Scanning %s ...\n", bdev->name);
+			dprintf(SPEW, "%s\n", mountpoint);
+			lk2nd_print_file_tree(mountpoint, " ");
+		}
+
+		lk2nd_try_extlinux(mountpoint);
+	}
+}
+
+/**
+ * lk2nd_boot() - Try to boot the OS.
+ *
+ * This method is supposed to be called from aboot.
+ * If appropriate OS is found, it will be booted, and this
+ * method will never return.
+ */
+void lk2nd_boot(void)
+{
+	static bool init_done = false;
+
+	if (!init_done) {
+		lk2nd_bdev_init();
+		init_done = true;
+	}
+
+	lk2nd_scan_devices();
+}

lk2nd/boot/boot.h

@@ -0,0 +1,16 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+#ifndef LK2ND_BOOT_BOOT_H
+#define LK2ND_BOOT_BOOT_H
+
+#include <list.h>
+#include <string.h>
+
+#include <lk2nd/boot.h>
+
+/* util.c */
+void lk2nd_print_file_tree(char *root, char *prefix);
+
+/* extlinux.c */
+void lk2nd_try_extlinux(const char *mountpoint);
+
+#endif /* LK2ND_BOOT_BOOT_H */