detect and handle emmc-backed xbl partitions when switching slots

bootctrl_impl.cpp

@@ -602,13 +602,16 @@ int set_active_boot_slot(unsigned slot)
 	uint32_t i;
 	int rc = -1;
 	map<string, vector<string> >::iterator map_iter;
+	bool ismmc;
 
 	if (boot_control_check_slot_sanity(slot)) {
 		fprintf(stderr, "%s: Bad arguments\n", __func__);
 		goto error;
 	}
 
-	if (ufs_bsg_dev_open() < 0) {
+	ismmc = gpt_utils_is_partition_backed_by_emmc(PTN_XBL AB_SLOT_A_SUFFIX);
+
+	if (!ismmc && ufs_bsg_dev_open() < 0) {
 		goto error;
 	}
 
@@ -618,7 +621,7 @@ int set_active_boot_slot(unsigned slot)
 	//in the list.
 	for (i = 0; i < ARRAY_SIZE(ptn_list); i++) {
 		//XBL is handled differrently for ufs devices so ignore it
-		if (!strncmp(ptn_list[i], PTN_XBL, strlen(PTN_XBL)))
+		if (!ismmc && !strncmp(ptn_list[i], PTN_XBL, strlen(PTN_XBL)))
 			continue;
 		//The partition list will be the list of _a partitions
 		string cur_ptn = ptn_list[i];
@@ -650,6 +653,10 @@ int set_active_boot_slot(unsigned slot)
 		}
 	}
 
+	// EMMC doesn't need attributes to be set.
+	if (ismmc)
+		return 0;
+
 	if (!strncmp(slot_suffix_arr[slot], AB_SLOT_A_SUFFIX,
 			strlen(AB_SLOT_A_SUFFIX))) {
 		//Set xbl_a as the boot lun

gpt-utils.cpp

@@ -781,3 +781,18 @@ error:
 		close(fd);
 	return -1;
 }
+
+//Determine whether to handle the given partition as eMMC or UFS, using the
+//name of the backing device.
+//
+//Note: In undefined cases (i.e. /dev/mmcblk1 and unresolvable), this function
+//will tend to prefer UFS behavior. If it incorrectly reports this, then the
+//program should exit (e.g. by failing) before making any changes.
+bool gpt_utils_is_partition_backed_by_emmc(const char *part) {
+	char devpath[PATH_MAX] = { '\0' };
+
+	if (get_dev_path_from_partition_name(part, devpath, sizeof(devpath)))
+		return false;
+
+	return !strcmp(devpath, EMMC_DEVICE);
+}

gpt-utils.h

@@ -84,6 +84,8 @@ extern "C" {
 		"product"
 #define BOOT_DEV_DIR  "/dev/disk/by-partlabel"
 
+#define EMMC_DEVICE "/dev/mmcblk0"
+
 #define ARRAY_SIZE(x) (sizeof(x) / sizeof((x)[0]))
 
 enum gpt_instance { PRIMARY_GPT = 0, SECONDARY_GPT };
@@ -163,6 +165,8 @@ int gpt_utils_set_xbl_boot_partition(enum boot_chain chain);
 int gpt_utils_get_partition_map(
 	std::vector<std::string> &partition_list,
 	std::map<std::string, std::vector<std::string> > &partition_map);
+
+bool gpt_utils_is_partition_backed_by_emmc(const char *part);
 #ifdef __cplusplus
 }
 #endif