env: am57xx: Implement A/B boot process
Add support for A/B boot process on AM57xx based boards:
1. Define 'slot_suffix' variable (using 'ab_select' command)
2. Extend 'emmc_android_boot' boot command (add commands for A/B boot
process)
'ab_select' command is used to decide which slot should be used for
booting up. A/B metadata resides in 'misc' partition.
To activate the A/B boot process, the following config options must be
set:
CONFIG_ANDROID_AB=y
CONFIG_CMD_AB_SELECT=y
For successful A/B boot, the corresponding A/B infrastructure must be
involved on Android side [1] (including mounting system as root), and
disk must be partitioned accordingly.
When A/B boot is enabled, there are some known limitations currently
exist (not related to A/B patches, need to be implemented later):
1. The 'Verified Boot' sequence is not supported
2. dev path to system partition (system_a or system_b) is passed via
'bootargs' as 'root=' argument like 'root=/dev/mmcblk1p12', but
further we'll need to rework it with respect to dm-verity
requirements [2]
In case when A/B partitions are not present in system (and A/B boot is
enabled), boot up process will be terminated and next message will be
shown:
"boot_a(b) partition not found"
[1] https://source.android.com/devices/tech/ota/ab
[2] https://source.android.com/devices/tech/ota/ab/ab_implement#kernel
Signed-off-by: Ruslan Trofymenko <ruslan.trofymenko@linaro.org>
Signed-off-by: Igor Opaniuk <igor.opaniuk@gmail.com>
Signed-off-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Alistair Strachan <astrachan@google.com>
Reviewed-by: Sam Protsenko <semen.protsenko@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/include/environment/ti/boot.h b/include/environment/ti/boot.h
index 05bdbbc..54e9b2d 100644
--- a/include/environment/ti/boot.h
+++ b/include/environment/ti/boot.h
@@ -23,6 +23,18 @@
#define VBMETA_PART ""
#endif
+#if defined(CONFIG_CMD_AB_SELECT)
+#define COMMON_PARTS \
+ "name=boot_a,size=20M,uuid=${uuid_gpt_boot_a};" \
+ "name=boot_b,size=20M,uuid=${uuid_gpt_boot_b};" \
+ "name=system_a,size=1024M,uuid=${uuid_gpt_system_a};" \
+ "name=system_b,size=1024M,uuid=${uuid_gpt_system_b};"
+#else
+#define COMMON_PARTS \
+ "name=boot,size=20M,uuid=${uuid_gpt_boot};" \
+ "name=system,size=1024M,uuid=${uuid_gpt_system};"
+#endif
+
#ifndef PARTS_DEFAULT
/* Define the default GPT table for eMMC */
#define PARTS_DEFAULT \
@@ -38,8 +50,7 @@
"name=uboot-env,start=2432K,size=256K,uuid=${uuid_gpt_reserved};" \
"name=misc,size=128K,uuid=${uuid_gpt_misc};" \
"name=recovery,size=40M,uuid=${uuid_gpt_recovery};" \
- "name=boot,size=10M,uuid=${uuid_gpt_boot};" \
- "name=system,size=1024M,uuid=${uuid_gpt_system};" \
+ COMMON_PARTS \
"name=vendor,size=256M,uuid=${uuid_gpt_vendor};" \
VBMETA_PART \
"name=userdata,size=-,uuid=${uuid_gpt_userdata}"
@@ -58,6 +69,35 @@
#define AVB_VERIFY_CMD ""
#endif
+#define CONTROL_PARTITION "misc"
+
+#if defined(CONFIG_CMD_AB_SELECT)
+#define AB_SELECT \
+ "if part number mmc 1 " CONTROL_PARTITION " control_part_number; " \
+ "then " \
+ "echo " CONTROL_PARTITION \
+ " partition number:${control_part_number};" \
+ "ab_select slot_name mmc ${mmcdev}:${control_part_number};" \
+ "else " \
+ "echo " CONTROL_PARTITION " partition not found;" \
+ "exit;" \
+ "fi;" \
+ "setenv slot_suffix _${slot_name};" \
+ "if part number mmc ${mmcdev} system${slot_suffix} " \
+ "system_part_number; then " \
+ "setenv bootargs_ab " \
+ "ro root=/dev/mmcblk${mmcdev}p${system_part_number} " \
+ "rootwait init=/init skip_initramfs " \
+ "androidboot.slot_suffix=${slot_suffix};" \
+ "echo A/B cmdline addition: ${bootargs_ab};" \
+ "setenv bootargs ${bootargs} ${bootargs_ab};" \
+ "else " \
+ "echo system${slot_suffix} partition not found;" \
+ "fi;"
+#else
+#define AB_SELECT ""
+#endif
+
#define DEFAULT_COMMON_BOOT_TI_ARGS \
"console=" CONSOLEDEV ",115200n8\0" \
"fdtfile=undefined\0" \
@@ -86,10 +126,16 @@
"mmc dev $mmcdev; " \
"mmc rescan; " \
AVB_VERIFY_CHECK \
- "part start mmc ${mmcdev} boot boot_start; " \
- "part size mmc ${mmcdev} boot boot_size; " \
- "mmc read ${loadaddr} ${boot_start} ${boot_size}; " \
- "bootm ${loadaddr}#${fdtfile};\0 "
+ AB_SELECT \
+ "if part start mmc ${mmcdev} boot${slot_suffix} boot_start; " \
+ "then " \
+ "part size mmc ${mmcdev} boot${slot_suffix} " \
+ "boot_size; " \
+ "mmc read ${loadaddr} ${boot_start} ${boot_size}; " \
+ "bootm ${loadaddr}#${fdtfile}; " \
+ "else " \
+ "echo boot${slot_suffix} partition not found; " \
+ "fi;\0"
#ifdef CONFIG_OMAP54XX