Hi,
We use imx8MM mini EVK board for our development.
And one of our observation was, onboard emmc flash (16 GB) when selected , it boots slower than SD card (removable media) as a boot device.
SD card we use is: Micro SD card Samsung make : 32 GB .
First, we selected SD card (removable media) as boot device by setting the necessary DIP switches on imx8mm board. On serial-console, we got all the 'Bootstage' timing report just before msg "Starting kernel..."
Same we tried with emmc flash (using different DIP SW settings) but with same U-boot and linux images and found there is a difference of about 1 sec to boot M4 core. (In this case, our bootcmd had M4 booting first and then linux booting).
On observing the Bootstage timing report, it was found SPL (secondary program loader) takes about ~700 m-sec more time in emmc-flash as compared to SD card.
Any reasons for this to happen? (is it due to variations in emmc and SD card?).
We had impression, onboard flash will be faster than external SD card, but it does not seem to be correct.
Also, please let us know where to look for emmc flash chip data sheet.
Regards,
Krishnakant Mehta
