I found the resolution for it. If we update the bootloader to use grub2 instead of legacy grub it will then list all the options. Linux as well as Xen related options. For updating the bootloader I followed the steps mentioned in below link :-<div>
<br></div><div><a href="http://fedoraproject.org/wiki/Features/Grub2#From_an_Installed_System_with_Grub_Legacy">http://fedoraproject.org/wiki/Features/Grub2#From_an_Installed_System_with_Grub_Legacy</a></div><div><br></div>
<div><h4 style="margin:0px 0px 0.3em;padding:0.5em 0px 0.17em;background-image:none;border-bottom-style:none;font-size:14px;font-family:sans-serif"><span class="mw-headline" id="Testing_With_Chain_Loading" style="margin:0px;padding:0px">Testing With Chain Loading</span></h4>
<p style="margin:1ex 5ex 1ex 0px;padding:0px;font-size:12px;font-family:sans-serif;line-height:18px">GRUB2 includes a boot image that's loadable from GRUB Legacy, so you can try it out without wiping out your existing, working MBR. To set up GRUB2 without actually writing to the MBR, run</p>
<p style="margin:1ex 5ex 1ex 0px;padding:0px;font-size:12px;font-family:sans-serif;line-height:18px"><code style="margin:0px;padding:0px;background-color:rgb(249,249,249);font-size:2.4ex">grub2-install --grub-setup=/bin/true /dev/sda</code></p>
<h4 style="margin:0px 0px 0.3em;padding:0.5em 0px 0.17em;background-image:none;border-bottom-style:none;font-size:14px;font-family:sans-serif"><span class="mw-headline" id="Writing_to_the_MBR" style="margin:0px;padding:0px">Writing to the MBR</span></h4>
<p style="margin:1ex 5ex 1ex 0px;padding:0px;font-size:12px;font-family:sans-serif;line-height:18px">If that works, you can go on testing to writing to your MBR. Same steps as above, but don't tell grub to run the dummy setup program /bin/true</p>
<p style="margin:1ex 5ex 1ex 0px;padding:0px;font-size:12px;font-family:sans-serif;line-height:18px"><code style="margin:0px;padding:0px;background-color:rgb(249,249,249);font-size:2.4ex">grub2-install /dev/sda</code></p>
<p style="margin:1ex 5ex 1ex 0px;padding:0px;font-size:12px;font-family:sans-serif;line-height:18px">Congratulations! You've reached the point of no return! If you can't boot now you will need to run a rescue CD</p>
<p style="margin:1ex 5ex 1ex 0px;padding:0px;font-size:12px;font-family:sans-serif;line-height:18px"><br></p><p style="margin:1ex 5ex 1ex 0px;padding:0px;font-size:12px;font-family:sans-serif;line-height:18px">Regards,</p>
<p style="margin:1ex 5ex 1ex 0px;padding:0px;font-size:12px;font-family:sans-serif;line-height:18px">~Sorabh</p><br><div class="gmail_quote">On Mon, Jun 11, 2012 at 11:27 AM, Konrad Rzeszutek Wilk <span dir="ltr"><<a href="mailto:konrad.wilk@oracle.com" target="_blank">konrad.wilk@oracle.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div class="im">On Sat, Jun 09, 2012 at 02:37:32PM +0300, Pasi Kärkkäinen wrote:<br>
> On Fri, Jun 08, 2012 at 12:00:44AM -0700, sorabh hamirwasia wrote:<br>
> > Hi,<br>
> > I have installed "Xen" on Fedora16 host using "yum install xen" command<br>
> > and it has been installed properly. I can see the changes in<br>
> > /etc/grub2.cfg file too. But when I reboot then the entry for Xen is not<br>
> > listed in the boot menu. On further analyzing I found that in<br>
> > /etc/grub.conf there is no entry related to Xen. Do we need to modify<br>
<br>
</div>Wouldn't it be in /boot/grub2/grub.cfg ?<br>
<div class="HOEnZb"><div class="h5"><br>
> > grub.conf manually ? If yes then how to do that. ?<br>
> > Please help me with this.<br>
> ><br>
><br>
> You can tweak the Xen hypervisor cmdline options in:<br>
> /etc/default/grub file, like this:<br>
><br>
> GRUB_DEFAULT="Xen"<br>
> GRUB_CMDLINE_XEN="dom0_mem=1024M,max:1024M loglvl=all guest_loglvl=all"<br>
><br>
> .. or whatever options you want to use.<br>
> After that update the grub menu: grub2-mkconfig -o /boot/grub2/grub.cfg<br>
><br>
> -- Pasi<br>
><br>
</div></div><span class="HOEnZb"><font color="#888888">> --<br>
> xen mailing list<br>
> <a href="mailto:xen@lists.fedoraproject.org">xen@lists.fedoraproject.org</a><br>
> <a href="https://admin.fedoraproject.org/mailman/listinfo/xen" target="_blank">https://admin.fedoraproject.org/mailman/listinfo/xen</a><br>
</font></span></blockquote></div><br><br clear="all"><div><br></div>-- <br>Regards,<br>Sorabh <br>
</div>