The options and arguments supplied while booting RHEL/CentOS kernel can be viewed in the file /proc/cmdline.
# cat /proc/cmdline ro root=/dev/mapper/vg_os-lv_os rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=131M@0M rd_LVM_LV=vg_os/lv_os KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet
Comparing with the default boot parameters
You can compare the /etc/grub.conf file with the /proc/cmdline file to see if the same options are used while booting the kernel. The /etc/cmdline is very useful to find if the kernel has been booted using any different parameters/arguments than that defined in the /etc/grun.conf file
# cat /etc/grub.conf # grub.conf generated by anaconda # # Note that you do not have to rerun grub after making changes to this file # NOTICE: You have a /boot partition. This means that # all kernel and initrd paths are relative to /boot/, eg. # root (hd0,0) # kernel /vmlinuz-version ro root=/dev/mapper/vg_os-lv_os # initrd /initrd-[generic-]version.img #boot=/dev/sda default=0 timeout=5 splashimage=(hd0,0)/grub/splash.xpm.gz hiddenmenu title Red Hat Enterprise Linux 6 (2.6.32-504.el6.x86_64) root (hd0,0) kernel /vmlinuz-2.6.32-504.el6.x86_64 ro root=/dev/mapper/vg_os-lv_os rd_NO_LUKS LANG=en_US.UTF-8 rd_NO_MD SYSFONT=latarcyrheb-sun16 crashkernel=auto rd_LVM_LV=vg_os/lv_os KEYBOARDTYPE=pc KEYTABLE=us rd_NO_DM rhgb quiet initrd /initramfs-2.6.32-504.el6.x86_64.img