how to replace kernel on Ubuntu

[loody]

hi all:

2009/10/10 NoOp <glgxg at sbcglobal.net>:
> On 10/09/2009 02:08 AM, loody wrote:
>> Dear all:
>> I try to replace the kernel under my Ubuntu.
>> my questions are:
>> 1. what is UUID used for? It seems replace "root=/dev/sda1"
>>     is there any tool or command I have to do to getting this number?
>> 2. from 2.6, we use initramfs instead of initrd, but why we still need
>> to add "initrd" option in menu.lst.
>> 3. is there any restriction of kernel version to replace in Ubuntu; if
>> I replace my ubuntu with older version as 2.6.18, will it be ok?
>> appreciate your help,
>> miloody
>>
>
> Maybe these will help:
>
> https://help.ubuntu.com/
> 1. Enter 'UUID' in the search bar.
> <https://help.ubuntu.com/community/UsingUUID>
> 2. Enter 'initrd' in the search bar. Click on 'Technical'
> <http://manpages.ubuntu.com/manpages/jaunty/man7/bootparam.7.html>
> Also:
> http://www.gnu.org/software/grub/manual/html_node/index.html
> 3. Don't know.
thanks for your all kind help :)
miloody