[U-Boot] U-Boot loading kernel from mmc question
I am trying to figure out how the bootm command in U-Boot works. It seems to be a state machine that goes from start->findos->findother (fdt)->loados etc.
However I am having trouble understanding how, since my linux image is stored in some partition on the device (eMMC), does that get loaded into memory?
Originally I thought this was what bootm_find_os and bootm_load_os does, but they don't seem to access the block devices or filesystem or contain code that reads in the linux and fdt images into memory.
Am I missing a step here?
-- View this message in context: http://u-boot.10912.n7.nabble.com/U-Boot-loading-kernel-from-mmc-question-tp... Sent from the U-Boot mailing list archive at Nabble.com.
Dear quantumlight,
In message 1455856589187-246390.post@n7.nabble.com you wrote:
I am trying to figure out how the bootm command in U-Boot works. It seems to be a state machine that goes from start->findos->findother (fdt)->loados etc.
However I am having trouble understanding how, since my linux image is stored in some partition on the device (eMMC), does that get loaded into memory?
No, it doesn't. The 'm' inte "bootm" command name stands for "memory", i. e. "boot from memory". Bootm is used on images that can be found somewhere in the processor's memor address space. So unless you have parallel NOR flash or similar, booting is always a two step procedure: in the first step you load the image from MMC into RAM, then you use bootm.
Best regards,
Wolfgang Denk
participants (2)
-
quantumlight -
Wolfgang Denk