Allow the use of a custom Android DT directory
On platforms that use ACPI instead of Device Tree (DT), such as
Ranchu x86/x86_64, /proc/device-tree/firmware/android/ does not
exist. As a result, Android O is unable to mount /system, etc.
at the first stage of init:
init: First stage mount skipped (missing/incompatible fstab in
device tree)
Those platforms may create another directory that mimics the layout
of the standard DT directory in procfs, and store early mount
configuration there. E.g., Ranchu x86/x86_64 creates one in sysfs
using information encoded in the ACPI tables:
https://android-review.googlesource.com/442472
https://android-review.googlesource.com/443432
https://android-review.googlesource.com/442393
https://android-review.googlesource.com/442395
Therefore, instead of hardcoding the Android DT path, load it from
the kernel command line using a new Android-specific property key
("androidboot.android_dt_dir"). If no such property exists, fall
back to the standard procfs path (so no change is needed for DT-
aware platforms).
Note that init/ and fs_mgr/ each have their own copy of the Android
DT path, because they do not share any global state. A future CL
should remove the duplication by refactoring.
With this CL as well as the above ones, the said warning is gone,
but early mount fails. That is a separate bug, though, and will be
addressed by another CL.
Test: Boot patched sdk_phone_x86-userdebug system image with patched
Goldfish 3.18 x86 kernel in patched Android Emulator, verify
the "init: First stage mount skipped" warning no longer shows
in dmesg.
Change-Id: Ib6df577319503ec1ca778de2b5458cc72ce07415
Signed-off-by: Yu Ning <yu.ning@intel.com>
diff --git a/fs_mgr/fs_mgr_boot_config.cpp b/fs_mgr/fs_mgr_boot_config.cpp
index 9117667..9c5d3f3 100644
--- a/fs_mgr/fs_mgr_boot_config.cpp
+++ b/fs_mgr/fs_mgr_boot_config.cpp
@@ -23,19 +23,11 @@
#include "fs_mgr_priv.h"
-// Tries to get the boot config value in properties, kernel cmdline and
-// device tree (in that order). returns 'true' if successfully found, 'false'
-// otherwise
-bool fs_mgr_get_boot_config(const std::string& key, std::string* out_val) {
+// Tries to get the given boot config value from kernel cmdline.
+// Returns true if successfully found, false otherwise.
+bool fs_mgr_get_boot_config_from_kernel_cmdline(const std::string& key, std::string* out_val) {
FS_MGR_CHECK(out_val != nullptr);
- // first check if we have "ro.boot" property already
- *out_val = android::base::GetProperty("ro.boot." + key, "");
- if (!out_val->empty()) {
- return true;
- }
-
- // fallback to kernel cmdline, properties may not be ready yet
std::string cmdline;
std::string cmdline_key("androidboot." + key);
if (android::base::ReadFileToString("/proc/cmdline", &cmdline)) {
@@ -50,9 +42,29 @@
}
}
+ return false;
+}
+
+// Tries to get the boot config value in properties, kernel cmdline and
+// device tree (in that order). returns 'true' if successfully found, 'false'
+// otherwise
+bool fs_mgr_get_boot_config(const std::string& key, std::string* out_val) {
+ FS_MGR_CHECK(out_val != nullptr);
+
+ // first check if we have "ro.boot" property already
+ *out_val = android::base::GetProperty("ro.boot." + key, "");
+ if (!out_val->empty()) {
+ return true;
+ }
+
+ // fallback to kernel cmdline, properties may not be ready yet
+ if (fs_mgr_get_boot_config_from_kernel_cmdline(key, out_val)) {
+ return true;
+ }
+
// lastly, check the device tree
if (is_dt_compatible()) {
- std::string file_name = kAndroidDtDir + "/" + key;
+ std::string file_name = get_android_dt_dir() + "/" + key;
if (android::base::ReadFileToString(file_name, out_val)) {
if (!out_val->empty()) {
out_val->pop_back(); // Trims the trailing '\0' out.
diff --git a/fs_mgr/fs_mgr_fstab.cpp b/fs_mgr/fs_mgr_fstab.cpp
index b68875b..8f5d3ad 100644
--- a/fs_mgr/fs_mgr_fstab.cpp
+++ b/fs_mgr/fs_mgr_fstab.cpp
@@ -29,6 +29,8 @@
#include "fs_mgr_priv.h"
+const std::string kDefaultAndroidDtDir("/proc/device-tree/firmware/android");
+
struct fs_mgr_flag_values {
char *key_loc;
char *verity_loc;
@@ -313,9 +315,26 @@
return f;
}
+static std::string init_android_dt_dir() {
+ std::string android_dt_dir;
+ // The platform may specify a custom Android DT path in kernel cmdline
+ if (!fs_mgr_get_boot_config_from_kernel_cmdline("android_dt_dir", &android_dt_dir)) {
+ // Fall back to the standard procfs-based path
+ android_dt_dir = kDefaultAndroidDtDir;
+ }
+ return android_dt_dir;
+}
+
+// FIXME: The same logic is duplicated in system/core/init/
+const std::string& get_android_dt_dir() {
+ // Set once and saves time for subsequent calls to this function
+ static const std::string kAndroidDtDir = init_android_dt_dir();
+ return kAndroidDtDir;
+}
+
static bool is_dt_fstab_compatible() {
std::string dt_value;
- std::string file_name = kAndroidDtDir + "/fstab/compatible";
+ std::string file_name = get_android_dt_dir() + "/fstab/compatible";
if (read_dt_file(file_name, &dt_value)) {
if (dt_value == "android,fstab") {
return true;
@@ -331,7 +350,7 @@
return fstab;
}
- std::string fstabdir_name = kAndroidDtDir + "/fstab";
+ std::string fstabdir_name = get_android_dt_dir() + "/fstab";
std::unique_ptr<DIR, int (*)(DIR*)> fstabdir(opendir(fstabdir_name.c_str()), closedir);
if (!fstabdir) return fstab;
@@ -394,7 +413,7 @@
}
bool is_dt_compatible() {
- std::string file_name = kAndroidDtDir + "/compatible";
+ std::string file_name = get_android_dt_dir() + "/compatible";
std::string dt_value;
if (read_dt_file(file_name, &dt_value)) {
if (dt_value == "android,firmware") {
diff --git a/fs_mgr/fs_mgr_priv.h b/fs_mgr/fs_mgr_priv.h
index 5ea6e98..7423c1f 100644
--- a/fs_mgr/fs_mgr_priv.h
+++ b/fs_mgr/fs_mgr_priv.h
@@ -119,6 +119,7 @@
const std::chrono::milliseconds relative_timeout);
bool fs_mgr_update_for_slotselect(struct fstab *fstab);
bool fs_mgr_is_device_unlocked();
+const std::string& get_android_dt_dir();
bool is_dt_compatible();
bool is_device_secure();
int load_verity_state(struct fstab_rec* fstab, int* mode);
diff --git a/fs_mgr/fs_mgr_priv_boot_config.h b/fs_mgr/fs_mgr_priv_boot_config.h
index 8773d33..d98dc02 100644
--- a/fs_mgr/fs_mgr_priv_boot_config.h
+++ b/fs_mgr/fs_mgr_priv_boot_config.h
@@ -20,8 +20,7 @@
#include <sys/cdefs.h>
#include <string>
-const std::string kAndroidDtDir("/proc/device-tree/firmware/android");
-
+bool fs_mgr_get_boot_config_from_kernel_cmdline(const std::string& key, std::string* out_val);
bool fs_mgr_get_boot_config(const std::string& key, std::string* out_val);
#endif /* __CORE_FS_MGR_PRIV_BOOTCONFIG_H */
diff --git a/init/init.cpp b/init/init.cpp
index f937777..51a3aaa 100644
--- a/init/init.cpp
+++ b/init/init.cpp
@@ -513,7 +513,7 @@
return;
}
- std::unique_ptr<DIR, int (*)(DIR*)> dir(opendir(kAndroidDtDir.c_str()), closedir);
+ std::unique_ptr<DIR, int (*)(DIR*)> dir(opendir(get_android_dt_dir().c_str()), closedir);
if (!dir) return;
std::string dt_file;
@@ -523,7 +523,7 @@
continue;
}
- std::string file_name = kAndroidDtDir + dp->d_name;
+ std::string file_name = get_android_dt_dir() + dp->d_name;
android::base::ReadFileToString(file_name, &dt_file);
std::replace(dt_file.begin(), dt_file.end(), ',', '.');
diff --git a/init/util.cpp b/init/util.cpp
index 2792794..fdcb22d 100644
--- a/init/util.cpp
+++ b/init/util.cpp
@@ -53,6 +53,8 @@
namespace android {
namespace init {
+const std::string kDefaultAndroidDtDir("/proc/device-tree/firmware/android/");
+
// DecodeUid() - decodes and returns the given string, which can be either the
// numeric or name representation, into the integer uid or gid. Returns
// UINT_MAX on error.
@@ -374,10 +376,31 @@
DoReboot(ANDROID_RB_RESTART2, "reboot", "bootloader", false);
}
-// Reads the content of device tree file under kAndroidDtDir directory.
+static std::string init_android_dt_dir() {
+ // Use the standard procfs-based path by default
+ std::string android_dt_dir = kDefaultAndroidDtDir;
+ // The platform may specify a custom Android DT path in kernel cmdline
+ import_kernel_cmdline(false,
+ [&](const std::string& key, const std::string& value, bool in_qemu) {
+ if (key == "androidboot.android_dt_dir") {
+ android_dt_dir = value;
+ }
+ });
+ LOG(INFO) << "Using Android DT directory " << android_dt_dir;
+ return android_dt_dir;
+}
+
+// FIXME: The same logic is duplicated in system/core/fs_mgr/
+const std::string& get_android_dt_dir() {
+ // Set once and saves time for subsequent calls to this function
+ static const std::string kAndroidDtDir = init_android_dt_dir();
+ return kAndroidDtDir;
+}
+
+// Reads the content of device tree file under the platform's Android DT directory.
// Returns true if the read is success, false otherwise.
bool read_android_dt_file(const std::string& sub_path, std::string* dt_content) {
- const std::string file_name = kAndroidDtDir + sub_path;
+ const std::string file_name = get_android_dt_dir() + sub_path;
if (android::base::ReadFileToString(file_name, dt_content)) {
if (!dt_content->empty()) {
dt_content->pop_back(); // Trims the trailing '\0' out.
diff --git a/init/util.h b/init/util.h
index 452df2d..29c10cb 100644
--- a/init/util.h
+++ b/init/util.h
@@ -30,8 +30,6 @@
#define COLDBOOT_DONE "/dev/.coldboot_done"
-const std::string kAndroidDtDir("/proc/device-tree/firmware/android/");
-
using android::base::boot_clock;
using namespace std::chrono_literals;
@@ -57,7 +55,10 @@
void panic() __attribute__((__noreturn__));
-// Reads or compares the content of device tree file under kAndroidDtDir directory.
+// Returns the platform's Android DT directory as specified in the kernel cmdline.
+// If the platform does not configure a custom DT path, returns the standard one (based in procfs).
+const std::string& get_android_dt_dir();
+// Reads or compares the content of device tree file under the platform's Android DT directory.
bool read_android_dt_file(const std::string& sub_path, std::string* dt_content);
bool is_android_dt_value_expected(const std::string& sub_path, const std::string& expected_content);