On Fri, May 05, 2017 at 04:58:27PM -0400, Aditya Basu wrote:

quoted

I am trying to compile and boot Linux Kernel v3.19 (64-bit version)

using -

quoted

make defconfig
make kvmconfig
make -j8

The compilation works out without any errors but it doesn't boot
inside qemu or my host machine.
I use the following command line parameters to linux: "debug
earlyprintk loglevel=7"

# The boot hangs at the point -
####################################
Booting from ROM...
early console in setup code
early console in decompress_kernel

Decompressing Linux... Parking ELF... done.
Booting the kernel .
####################################

# Things I have tried so far:
- Interestingly if I uncheck the 64-bit build in config (from make
menuconfig), the resulting 32-bit kernel boots correctly.

- Have tried running qemu with different cpus (host) + with & without

kvm.

quoted

sudo qemu-system-x86_64 -m 4G -append 'debug earlyprintk loglevel=7'
-kernel arch/x86/boot/bzImage -cpu host -enable-kvm

I know the kernel will panic because of no root filesystem, but it
happens later in the boot process. I am basing this from booting the
32 bit version of the kernel which prints out a lot of stuff and then
panics due to no vfs_root.

- The 64-bit versions of kernel v4.2 and above don't have this issue -
meaning they boot correctly.

Great!  Stick with newer kernels, 3.19 is really old, as is 4.2, lots
and lots of things have been fixed since then, you aren't going to be
able to get any help from anyone in the community if you use old kernels
like that, sorry.

?My primary goal is to build and boot LLVM Linux (
http://llvm.linuxfoundation.org/index.php/Main_Page). This project has
patches available only till kernel v3.19. That's why I am trying to use the
older version 3.19.
?

quoted

Any pointers to what the mistake is?

*Linux Kernel Repo used*
git://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git

That has all kernel releases _ever_, you need to be a bit more specific
as to the branch you are using :)

?I checkout on the tag _v3.19_.

good luck!

greg k-h

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