From 947a7d6a2fb5d83e0fad4523ab0890d690745764 Mon Sep 17 00:00:00 2001
From: Billy Laws <blaws05@gmail.com>
Date: Wed, 30 Dec 2020 11:56:40 +0000
Subject: [PATCH] Support rootwait cmdline parameter on legacy SAR

On devices where the primary storage is slow to probe it makes sense to
wait forever for the system partition to mount, this emulates the
kernel's behaviour when waiting for rootfs on SAR if the rootwait
parameter is supplied.

This issue was encountered with some SD cards on the Nintendo Switch.
---
 native/jni/init/getinfo.cpp |  3 +++
 native/jni/init/init.hpp    |  1 +
 native/jni/init/mount.cpp   | 33 +++++++++++++++++++--------------
 3 files changed, 23 insertions(+), 14 deletions(-)

diff --git a/native/jni/init/getinfo.cpp b/native/jni/init/getinfo.cpp
index ea471cde4..1b23f3f65 100644
--- a/native/jni/init/getinfo.cpp
+++ b/native/jni/init/getinfo.cpp
@@ -160,6 +160,8 @@ void load_kernel_info(cmdline *cmd) {
 			cmd->skip_initramfs = true;
 		} else if (key == "androidboot.force_normal_boot") {
 			cmd->force_normal_boot = value[0] == '1';
+		} else if (key == "rootwait") {
+			cmd->rootwait = true;
 		} else if (key == "androidboot.android_dt_dir") {
 			strcpy(cmd->dt_dir, value);
 		} else if (key == "androidboot.hardware") {
@@ -174,6 +176,7 @@ void load_kernel_info(cmdline *cmd) {
 	LOGD("Kernel cmdline info:\n");
 	LOGD("skip_initramfs=[%d]\n", cmd->skip_initramfs);
 	LOGD("force_normal_boot=[%d]\n", cmd->force_normal_boot);
+	LOGD("rootwait=[%d]\n", cmd->rootwait);
 	LOGD("slot=[%s]\n", cmd->slot);
 	LOGD("dt_dir=[%s]\n", cmd->dt_dir);
 	LOGD("fstab_suffix=[%s]\n", cmd->fstab_suffix);
diff --git a/native/jni/init/init.hpp b/native/jni/init/init.hpp
index d998da8b6..2b15c02af 100644
--- a/native/jni/init/init.hpp
+++ b/native/jni/init/init.hpp
@@ -5,6 +5,7 @@
 struct cmdline {
 	bool skip_initramfs;
 	bool force_normal_boot;
+	bool rootwait;
 	char slot[3];
 	char dt_dir[64];
 	char fstab_suffix[32];
diff --git a/native/jni/init/mount.cpp b/native/jni/init/mount.cpp
index 840e20251..ebea25c43 100644
--- a/native/jni/init/mount.cpp
+++ b/native/jni/init/mount.cpp
@@ -309,22 +309,27 @@ void SARBase::backup_files() {
 void SARBase::mount_system_root() {
 	LOGD("Early mount system_root\n");
 	strcpy(blk_info.block_dev, "/dev/root");
-	// Try legacy SAR dm-verity
-	strcpy(blk_info.partname, "vroot");
-	auto dev = setup_block(false);
-	if (dev >= 0)
-		goto mount_root;
 
-	// Try NVIDIA naming scheme
-	strcpy(blk_info.partname, "APP");
-	dev = setup_block(false);
-	if (dev >= 0)
-		goto mount_root;
+	do {
+		// Try legacy SAR dm-verity
+		strcpy(blk_info.partname, "vroot");
+		auto dev = setup_block(false);
+		if (dev >= 0)
+			goto mount_root;
 
-	sprintf(blk_info.partname, "system%s", cmd->slot);
-	dev = setup_block(false);
-	if (dev >= 0)
-		goto mount_root;
+		// Try NVIDIA naming scheme
+		strcpy(blk_info.partname, "APP");
+		dev = setup_block(false);
+		if (dev >= 0)
+			goto mount_root;
+
+		sprintf(blk_info.partname, "system%s", cmd->slot);
+		dev = setup_block(false);
+		if (dev >= 0)
+			goto mount_root;
+
+		// Poll forever if rootwait was given in cmdline
+	} while (cmd->rootwait);
 
 	// We don't really know what to do at this point...
 	LOGE("Cannot find root partition, abort\n");