Boot issues with custom 64-bit kernel v3.19

[Aditya Basu]

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

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.

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.

Any pointers to what the mistake is?

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

*My Config*
https://dl.dropboxusercontent.com/u/9020146/errors/linux_2017_05_05/config-used

* QEMU version*
QEMU emulator version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.11)


-- 
Regards,
Aditya Basu