Hi sandeep, On Sun, Jul 24, 2011 at 9:18 PM, sandeep kumar <coolsandyforyou@gmail.com> wrote:
Hi all, In Android target mobiles there is a facility called "Ramdump", where the entire Ram image is copied to a file as the kernel goes to panic.
Ramdump is implemented like this 1) As the panic() function is called target will be reset. 2) Bootloader boots up in specific mode, where it enables the USB driver in uploading mode. 3) Through USB entire RAM content is copied to a file in the host computer. 4) This file is parsed through different tools and we can get the logs info wat exactly happened just before kernel panic happend.
Now here is the interesting part, While the mobile's RAM image is being uploaded to host computer, our bootloader is still running in the mobile's RAM. How can it copy its own running region.
This triggered me the following questions,
1) When bootloader runs, will it run in a specific reserved region of RAM or it takes entire RAM?
Some do - it depends on the processor. Some processors have a bunch of internal static RAM that the bootloader runs out of.
2) When it hands over the control to kernel, will it relinquish the entire RAM or certain part of RAM is reserved for it?
Not sure.
3) Does kernel use the entire RAM while running?
It depends on how things are configured.
4) When the kernel is running, is ther any chance that, control again be taken back to bootloader?(coz i saw in bootloader code kernel is being called,
after that code also some code is there,some printks and error handling stuff)
I don't think that the kernel ever gives control back to the bootloader. -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com