host system is :ubuntu server 14.04.2
lfs 7.6

this is the last line on the boot screen when i boot my lfs
---[ end Kernel panic -not syncing: VFS:Unable to mount root fs on unknown-block(0,0)

How you have setup partitions and boot partitions?

Are you using initrd/initramfs images?

What kernel parameters are you passing to grub?

single partition
/dev/sdb1 mounted on /mnt/lfs

built lfs strictly acc to book nothing mentioned about initrd/initramfs images

not passing any parameters to grub just selected the lfs i built on the boot screen

So you must have first configured the boot screen. How you did that. Or post the content of file '/boot/grub/grub.cfg'.

What is the type of /dev/sdb1 filesystem? Have you build the LFS kernel with that filesystem driver and not as module since you are not using initrd/initramfs?

#
# DO NOT EDIT THIS FILE
#
# It is automatically generated by grub-mkconfig using templates
# from /etc/grub.d and settings from /etc/default/grub
#

### BEGIN /etc/grub.d/00_header ###
if [ -s $prefix/grubenv ]; then
set have_grubenv=true
load_env
fi
if [ "${next_entry}" ] ; then
set default="${next_entry}"
set next_entry=
save_env next_entry
set boot_once=true
else
set default="0"
fi

if [ x"${feature_menuentry_id}" = xy ]; then
menuentry_id_option="--id"
else
menuentry_id_option=""
fi

export menuentry_id_option

if [ "${prev_saved_entry}" ]; then
set saved_entry="${prev_saved_entry}"
save_env saved_entry
set prev_saved_entry=
save_env prev_saved_entry
set boot_once=true
fi

function savedefault {
if [ -z "${boot_once}" ]; then
saved_entry="${chosen}"
save_env saved_entry
fi
}
function recordfail {
set recordfail=1
if [ -n "${have_grubenv}" ]; then if [ -z "${boot_once}" ]; then save_env recordfail; fi; fi
}
function load_video {
if [ x$feature_all_video_module = xy ]; then
insmod all_video
else
insmod efi_gop
insmod efi_uga
insmod ieee1275_fb
insmod vbe
insmod vga
insmod video_bochs
insmod video_cirrus
fi
}

if [ x$feature_default_font_path = xy ] ; then
font=unicode
else
insmod part_msdos
insmod lvm
insmod ext2
set root='lvmid/eNwtzB-4Fb2-1NBN-4ewU-Eynf-uf1l-UDHZJE/Q6De9Z-UGTB-RAjT-CZsp-Uw4g-bg9G-YbBOZo'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint='lvmid/eNwtzB-4Fb2-1NBN-4ewU-Eynf-uf1l-UDHZJE/Q6De9Z-UGTB-RAjT-CZsp-Uw4g-bg9G-YbBOZo' e7772e88-6fee-4eb2-89e6-60d9214b721e
else
search --no-floppy --fs-uuid --set=root e7772e88-6fee-4eb2-89e6-60d9214b721e
fi
font="/share/grub/unicode.pf2"
fi

if loadfont $font ; then
set gfxmode=auto
load_video
insmod gfxterm
set locale_dir=$prefix/locale
set lang=en_US
insmod gettext
fi
terminal_output gfxterm
if [ "${recordfail}" = 1 ] ; then
set timeout=-1
else
if [ x$feature_timeout_style = xy ] ; then
set timeout_style=menu
set timeout=2
# Fallback normal timeout code in case the timeout_style feature is
# unavailable.
else
set timeout=2
fi
fi
### END /etc/grub.d/00_header ###

### BEGIN /etc/grub.d/05_debian_theme ###
set menu_color_normal=white/black
set menu_color_highlight=black/light-gray
### END /etc/grub.d/05_debian_theme ###

### BEGIN /etc/grub.d/10_linux ###
function gfxmode {
set gfxpayload="${1}"
if [ "${1}" = "keep" ]; then
set vt_handoff=vt.handoff=7
else
set vt_handoff=
fi
}
if [ "${recordfail}" != 1 ]; then
if [ -e ${prefix}/gfxblacklist.txt ]; then
if hwmatch ${prefix}/gfxblacklist.txt 3; then
if [ ${match} = 0 ]; then
set linux_gfx_mode=keep
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=text
fi
else
set linux_gfx_mode=keep
fi
else
set linux_gfx_mode=text
fi
export linux_gfx_mode
menuentry 'Ubuntu' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-simple-d69f90e9-ffbe-4c30-8fd1-db376d304f27' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 db39c05e-1087-4119-bd45-bf083e082cf3
else
search --no-floppy --fs-uuid --set=root db39c05e-1087-4119-bd45-bf083e082cf3
fi
linux /vmlinuz-3.16.0-30-generic root=/dev/mapper/ubuntu--vg-root ro find_preseed=/preseed.cfg noprompt
initrd /initrd.img-3.16.0-30-generic
}
submenu 'Advanced options for Ubuntu' $menuentry_id_option 'gnulinux-advanced-d69f90e9-ffbe-4c30-8fd1-db376d304f27' {
menuentry 'Ubuntu, with Linux 3.16.0-30-generic' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.16.0-30-generic-advanced-d69f90e9-ffbe-4c30-8fd1-db376d304f27' {
recordfail
load_video
gfxmode $linux_gfx_mode
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 db39c05e-1087-4119-bd45-bf083e082cf3
else
search --no-floppy --fs-uuid --set=root db39c05e-1087-4119-bd45-bf083e082cf3
fi
echo 'Loading Linux 3.16.0-30-generic ...'
linux /vmlinuz-3.16.0-30-generic root=/dev/mapper/ubuntu--vg-root ro find_preseed=/preseed.cfg noprompt
echo 'Loading initial ramdisk ...'
initrd /initrd.img-3.16.0-30-generic
}
menuentry 'Ubuntu, with Linux 3.16.0-30-generic (recovery mode)' --class ubuntu --class gnu-linux --class gnu --class os $menuentry_id_option 'gnulinux-3.16.0-30-generic-recovery-d69f90e9-ffbe-4c30-8fd1-db376d304f27' {
recordfail
load_video
insmod gzio
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 db39c05e-1087-4119-bd45-bf083e082cf3
else
search --no-floppy --fs-uuid --set=root db39c05e-1087-4119-bd45-bf083e082cf3
fi
echo 'Loading Linux 3.16.0-30-generic ...'
linux /vmlinuz-3.16.0-30-generic root=/dev/mapper/ubuntu--vg-root ro recovery nomodeset find_preseed=/preseed.cfg noprompt
echo 'Loading initial ramdisk ...'
initrd /initrd.img-3.16.0-30-generic
}
}

### END /etc/grub.d/10_linux ###

### BEGIN /etc/grub.d/20_linux_xen ###

### END /etc/grub.d/20_linux_xen ###

### BEGIN /etc/grub.d/20_memtest86+ ###
menuentry 'Memory test (memtest86+)' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 db39c05e-1087-4119-bd45-bf083e082cf3
else
search --no-floppy --fs-uuid --set=root db39c05e-1087-4119-bd45-bf083e082cf3
fi
knetbsd /memtest86+.elf
}
menuentry 'Memory test (memtest86+, serial console 115200)' {
insmod part_msdos
insmod ext2
set root='hd0,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd0,msdos1 --hint-efi=hd0,msdos1 --hint-baremetal=ahci0,msdos1 db39c05e-1087-4119-bd45-bf083e082cf3
else
search --no-floppy --fs-uuid --set=root db39c05e-1087-4119-bd45-bf083e082cf3
fi
linux16 /memtest86+.bin console=ttyS0,115200n8
}
### END /etc/grub.d/20_memtest86+ ###

### BEGIN /etc/grub.d/30_os-prober ###
menuentry 'unknown Linux distribution (on /dev/sdb1)' --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-simple-7faaffca-eb24-4e9d-bfe3-b3a19875ef1f' {
insmod part_msdos
insmod ext2
set root='hd1,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd1,msdos1 --hint-efi=hd1,msdos1 --hint-baremetal=ahci1,msdos1 7faaffca-eb24-4e9d-bfe3-b3a19875ef1f
else
search --no-floppy --fs-uuid --set=root 7faaffca-eb24-4e9d-bfe3-b3a19875ef1f
fi
linux /boot/vmlinuz-3.16.2-lfs-7.6 root=/dev/sdb1
}
submenu 'Advanced options for unknown Linux distribution (on /dev/sdb1)' $menuentry_id_option 'osprober-gnulinux-advanced-7faaffca-eb24-4e9d-bfe3-b3a19875ef1f' {
menuentry 'unknown Linux distribution (on /dev/sdb1)' --class gnu-linux --class gnu --class os $menuentry_id_option 'osprober-gnulinux-/boot/vmlinuz-3.16.2-lfs-7.6--7faaffca-eb24-4e9d-bfe3-b3a19875ef1f' {
insmod part_msdos
insmod ext2
set root='hd1,msdos1'
if [ x$feature_platform_search_hint = xy ]; then
search --no-floppy --fs-uuid --set=root --hint-bios=hd1,msdos1 --hint-efi=hd1,msdos1 --hint-baremetal=ahci1,msdos1 7faaffca-eb24-4e9d-bfe3-b3a19875ef1f
else
search --no-floppy --fs-uuid --set=root 7faaffca-eb24-4e9d-bfe3-b3a19875ef1f
fi
linux /boot/vmlinuz-3.16.2-lfs-7.6 root=/dev/sdb1
}
}

set timeout_style=menu
if [ "${timeout}" = 0 ]; then
set timeout=10
fi
### END /etc/grub.d/30_os-prober ###

### BEGIN /etc/grub.d/30_uefi-firmware ###
### END /etc/grub.d/30_uefi-firmware ###

### BEGIN /etc/grub.d/40_custom ###
# This file provides an easy way to add custom menu entries. Simply type the
# menu entries you want to add after this comment. Be careful not to change
# the 'exec tail' line above.
### END /etc/grub.d/40_custom ###

### BEGIN /etc/grub.d/41_custom ###
if [ -f ${config_directory}/custom.cfg ]; then
source ${config_directory}/custom.cfg
elif [ -z "${config_directory}" -a -f $prefix/custom.cfg ]; then
source $prefix/custom.cfg;
fi
### END /etc/grub.d/41_custom ###

file system ext4

LFS kernel with that filesystem driver and not as module since you are not using initrd/initramfs?
i think i missed this part i compiled kernel this way:
# copy, untar and set permissions
cp /sources/linux-3.0.0.tar.xz /usr/src/
cd /usr/src
tar linux-3.0.0.tar.xz
chmod -R 0:0 linux-3.0.0

# build the kernel
cd linux-3.0.0
make mrproper
make defconfig
make menuconfig

# install the kernel and associated files
make
make modules_install
cp -v arch/x86/boot/bzImage /boot/vmlinuz-3.0.0-lfs-7.0
cp -v System.map /boot/System.map-3.0.0
cp -v .config /boot/config-3.0.0

plz suggest how to correct this

Check this file for line like 'CONFIG_EXT4_FS=y'.

If it is there then you have it compiled it into the kernel.

Else while building in the 'make menuconfig' step go to drivers section and from there to filesystem section and compile ext4 as 'Y' not m (Module).

yes CONFIG_EXT4_FS=y is present in config-3.16.2

CONFIG_DCACHE_WORD_ACCESS=y
# CONFIG_EXT2_FS is not set
# CONFIG_EXT3_FS is not set
CONFIG_EXT4_FS=y
CONFIG_EXT4_USE_FOR_EXT23=y
CONFIG_EXT4_FS_POSIX_ACL=y
CONFIG_EXT4_FS_SECURITY=y
# CONFIG_EXT4_DEBUG is not set
CONFIG_JBD2=y
# CONFIG_JBD2_DEBUG is not set
CONFIG_FS_MBCACHE=y
# CONFIG_REISERFS_FS is not set
# CONFIG_JFS_FS is not set
# CONFIG_XFS_FS is not set
# CONFIG_GFS2_FS is not set

did you build this in the kernel

You have posted only one line of kernel panic message. Can you post some of the messages above and below the kernel panic line you have posted.

Also from inferring your posts you are using the ubuntu's installed grub to boot your LFS 7.6 kernel. Is it correct?

i think i did that acc to
#
# Generic Driver Options
#
CONFIG_UEVENT_HELPER=y
CONFIG_UEVENT_HELPER_PATH="/sbin/hotplug"
CONFIG_DEVTMPFS=y
CONFIG_DEVTMPFS_MOUNT=y
CONFIG_STANDALONE=y
CONFIG_PREVENT_FIRMWARE_BUILD=y
CONFIG_FW_LOADER=y
CONFIG_FIRMWARE_IN_KERNEL=y
CONFIG_EXTRA_FIRMWARE=""
CONFIG_FW_LOADER_USER_HELPER=y
# CONFIG_DEBUG_DRIVER is not set
CONFIG_DEBUG_DEVRES=y
# CONFIG_SYS_HYPERVISOR is not set
# CONFIG_GENERIC_CPU_DEVICES is not set
CONFIG_GENERIC_CPU_AUTOPROBE=y
CONFIG_DMA_SHARED_BUFFER=y

and i did perform the version check initially

Yes i am using ubuntu installed grub to boot

i attached a picture of boot messages

Attached Thumbnails

 

Block shouldn't be 0,0. Since in grub you have specified root=/dev/sdb1.

But from that image it is seen you are running Ubuntu as well as LFS in a VMware Virtual Platform.

Check in kernel config-3.0.0 file that MSDOS and GPT Partition support is available. Also check whether drivers for whatever Vmware emulates as disk drives is available. If you can somehow read the whole kernel boot message it would give a clue.

i think msdos support is available , but didnt found anything about gpt
#
# Partition Types
#
CONFIG_PARTITION_ADVANCED=y
# CONFIG_ACORN_PARTITION is not set
# CONFIG_AIX_PARTITION is not set
CONFIG_OSF_PARTITION=y
CONFIG_AMIGA_PARTITION=y
# CONFIG_ATARI_PARTITION is not set
CONFIG_MAC_PARTITION=y
CONFIG_MSDOS_PARTITION=y
CONFIG_BSD_DISKLABEL=y
CONFIG_MINIX_SUBPARTITION=y
CONFIG_SOLARIS_X86_PARTITION=y
CONFIG_UNIXWARE_DISKLABEL=y
# CONFIG_LDM_PARTITION is not set
CONFIG_SGI_PARTITION=y
# CONFIG_ULTRIX_PARTITION is not set
CONFIG_SUN_PARTITION=y
CONFIG_KARMA_PARTITION=y
CONFIG_EFI_PARTITION=y
# CONFIG_SYSV68_PARTITION is not set
# CONFIG_CMDLINE_PARTITION is not set

CONFIG_EFI_PARTITION=y is equivalent to GPT partition, should have given correct name.