[syslinux] memdisk - grub2

Shao Miller Shao.Miller at yrdsb.edu.on.ca
Thu Aug 11 13:30:44 PDT 2011

On 8/11/2011 16:00, Karl Schmidt wrote:
> On 08/11/2011 02:21 AM, Miller, Shao wrote:
>> And when I searched in Google with:
>>    "memdisk.mod" grub
>> This was one of the search results:
>>    http://lists.gnu.org/archive/html/help-grub/2011-02/msg00020.html
>> which appears to answer your question (hopefully) and confirm my last
>> response.
> Yes, I had seen this and tried it - it was his guess and did not work.

No, it's not his guess.  Perhaps you only read the quoted e-mail?  At 
the bottom is Jordan Uggla's response, which is what I was referring to 
and which is not a guess.  Did you read it?  If not, here it is:

On Fri, 18 Feb 2011 23:52:28 -0800, in thread "Re: memdisk", Jordan 
Uggla wrote:
> memdisk.mod is indeed just for loading a memdisk stored in the
> core.img, but you can use syslinux's memdisk with grub2. Syslinux's
> memdisk is loaded like a linux kernel (specifically using the 16 bit
> rather than 32 bit linux protocol). Instructions for using Syslinux's
> memdisk from GRUB2 can be found here:
> http://syslinux.zytor.com/wiki/index.php/MEMDISK#GRUB2 .

On 8/11/2011 16:00, Karl Schmidt wrote:
> I finally got it to work - this is not documented anywhere so I will 
> paste it in here for the next guy.

It appears to me like the link given above in Jordan's response 
documents "it."

> You only need insmod lvm and jfs if you are using lvm and jfs ... your 
> "set root=" will differ as well the directory paths. In /boot I put a 
> ln -s /usr/lib/syslinux/memdisk ,but one could use the full path.
> This is for grub2 - not grub. Located in /etc/grub.d/40_custom (you 
> need to run update-grub after any changes )
> #!/bin/sh
> exec tail -n +3 $0
> # 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.
> menuentry "Memtest-Plus 4.2" {
>         echo `hello`
>         insmod lvm
>         insmod part_msdos
>         insmod jfs
>         insmod memdisk
>         set root='(ssd-testing)'
>         search --no-floppy --fs-uuid --set 
> f9ae292b-b6a9-4f70-af7c-31987e766d37
>         linux16 /boot/memdisk iso
>         initrd16 /boot/memtest-plus/memtest86+-4.20.iso
> }

Could you please try this without 'insmod memdisk' and report if it 
works just the same?  I believe the key is having 'iso' on the 'linux16' 
line, but it'd be great if you could confirm.


- Shao Miller

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