[MinnowBoard] Recompiling the kernel of the "core-image-sato-sdk" image.

[Darren Hart]

On 7/1/15 4:50 PM, Vasanthi, Jagatha wrote:
>  Hello
> I'm downloaded the "core-image-sato-sdk" image on the Minnowboard MAX and have had no issues with it so far. But now, I have a need to change some configurations and recompile the kernel. The steps  seem to be working but when I reboot it keeps booting to the old kernel image. I'd like to understand how Minnowboard chooses the kernel image to boot. I looked for a grub config file but could not find it. I would appreciate any leads on this.
> 
> These are the steps I followed:
> 1. cd /usr/src/kernel
> 2. make menuconfig
> 3. made changes and saved them to the .config file
> 4. Changed EXTRAVERSION in Makefile to unique name
> 5. ran "make"
> 6. ran "make  modules"
> 7. ran  "make modules_install"
> 8. I tried to run "make install" at this point but it complained that it could not find LILO. So I tried the below steps

Interesting... haven't run into that. But I rarely build on target,
especially not entire kernels.

> 9. cp System.map /boot/System.map-PERFORMANCE 
> 10. ln -sf /boot/System.map-PERFORMANCE /boot/System.map
> 11. cp arch/x86_64/boot/bzImage /boot/

How are you booting? Which exact image and how did you copy it to your
boot media?

I suspect copying it to /boot has no effect because that is not the
kernel being booted by the boot loader. The hddimg is a fat image with
an EFI/BOOT directory for the bootx64.efi payload. The kernel is in the
top level directory of the hddimg, but this is NOT /boot. To copy
something there from the target itself, you need to mount it. If it's a
USB drive:

mount /dev/sda /some/path
cp bzImage /some/path/vmlinuz

I suggest calling it something else, like vmlinuz-test and modifying the
boot loader to add a target for -test, then if you mess it up, your
image will still boot.

> 12.  Rebooted but new changes did not take effect. I also tried 'uname -r' and did not see the EXTRAVERSION change that I made.
> 
> 
> When I reboot, I always get into the EFI shell , so I have to run "fs0:" and "bootx64". Is bootx64 a file that I can access and read?

bootx64 is in EFI/BOOT/bootx64.efi, you can make this your default boot
target by configuring the boot order in the UEFI firmware.

-- 
Darren Hart
Intel Open Source Technology Center