[RFC PATCH] bootstage: stash boot records to reserved mem before kernel handoff

[Vishnu Singh]

On 22/08/25 20:17, Tom Rini wrote:
> On Fri, Aug 22, 2025 at 09:35:23AM +0530, vishnu singh wrote:
>
>> From: Vishnu Singh <v-singh1 at ti.com>
>>
>> U-Boot now stashes its bootstage buffer into a reserved memory region
>> whenever CONFIG_BOOTSTAGE_STASH is enabled, just before exiting to the
>> kernel. This allows a post boot parser to read a unified timeline
>> (SPL→U-Boot→Kernel→MCU/DSP) directly from DDR, enabling standardized
>> and repeatable boot-time profiling across releases and SoCs.
>>
>> Change summary:
>>   Call bootstage_stash_default() in announce_and_cleanup()
>>    when CONFIG_BOOTSTAGE_STASH is set.
>>
>> Reference boot-time parser utility:
>>   https://github.com/v-singh1/boot-time-parse
>>
>> Sample boot time report:
>>      +--------------------------------------------------------------------+
>>                       am62xx-evm Boot Time Report
>>      +--------------------------------------------------------------------+
>>      Device Power On         : 0 ms
>>      SPL Time                : 843 ms
>>      U-Boot Time             : 2173 ms
>>      Kernel handoff time     : 462 ms
>>      Kernel Time             : 2522 ms
>>      Total Boot Time         : 6000 ms
>>      +--------------------------------------------------------------------+
>>
>>      +--------------------------------------------------------------------+
>>                       Bootloader and Kernel Boot Records
>>      +--------------------------------------------------------------------+
>>      BOOTSTAGE_AWAKE                =      0 ms (+  0 ms)
>>      BOOTSTAGE_START_UBOOT_F        =    843 ms (+  0 ms)
>>      BOOTSTAGE_ACCUM_DM_F           =    843 ms (+  0 ms)
>>      BOOTSTAGE_START_UBOOT_R        =   1951 ms (+1108 ms)
>>      BOOTSTAGE_ACCUM_DM_R           =   1951 ms (+  0 ms)
>>      BOOTSTAGE_NET_ETH_START        =   2032 ms (+ 81 ms)
>>      BOOTSTAGE_NET_ETH_INIT         =   2053 ms (+ 21 ms)
>>      BOOTSTAGE_MAIN_LOOP            =   2055 ms (+  2 ms)
>>      BOOTSTAGE_START_MCU            =   2661 ms (+606 ms)
>>      BOOTSTAGE_BOOTM_START          =   2959 ms (+298 ms)
>>      BOOTSTAGE_RUN_OS               =   3016 ms (+ 57 ms)
>>      BOOTSTAGE_BOOTM_HANDOFF        =   3016 ms (+  0 ms)
>>      BOOTSTAGE_KERNEL_START         =   3478 ms (+462 ms)
>>      BOOTSTAGE_KERNEL_END           =   6000 ms (+2522 ms)
>>      +--------------------------------------------------------------------+
>>
>>      +--------------------------------------------------------------------+
>>                       MCU Boot Records
>>      +--------------------------------------------------------------------+
>>      MCU_AWAKE                      =   2661 ms (+  0 ms)
>>      BOARD_PERIPHERALS_INIT         =   2661 ms (+  0 ms)
>>      MAIN_TASK_CREATE               =   2661 ms (+  0 ms)
>>      FIRST_TASK                     =   2662 ms (+  1 ms)
>>      DRIVERS_OPEN                   =   2662 ms (+  0 ms)
>>      BOARD_DRIVERS_OPEN             =   2662 ms (+  0 ms)
>>      IPC_SYNC_FOR_LINUX             =   6636 ms (+3974 ms)
>>      IPC_REGISTER_CLIENT            =   6636 ms (+  0 ms)
>>      IPC_SUSPEND_TASK               =   6636 ms (+  0 ms)
>>      IPC_RECEIVE_TASK               =   6636 ms (+  0 ms)
>>      IPC_SYNC_ALL                   =   6787 ms (+151 ms)
>>      +--------------------------------------------------------------------+
>>
>> Signed-off-by: Vishnu Singh <v-singh1 at ti.com>
> In that it looks like x86 already does a similar thing, this is a good
> idea and I wonder if some tooling already exists to read it.
>
>> ---
>>   arch/arm/lib/bootm.c | 3 +++
>>   1 file changed, 3 insertions(+)
>>
>> diff --git a/arch/arm/lib/bootm.c b/arch/arm/lib/bootm.c
>> index 7eb764e1f4e..b01e763ff28 100644
>> --- a/arch/arm/lib/bootm.c
>> +++ b/arch/arm/lib/bootm.c
>> @@ -57,6 +57,9 @@ static void announce_and_cleanup(int fake)
>>   #ifdef CONFIG_BOOTSTAGE_FDT
>>   	bootstage_fdt_add_report();
>>   #endif
>> +	if (IS_ENABLED(CONFIG_BOOTSTAGE_STASH))
>> +		bootstage_stash_default();
> You don't need to guard the call, the default bootstage_stash_default()
> is a return 0 call when CONFIG_BOOTSTAGE_STASH isn't set.
Will update and send the patch