[syslinux] EXTLINUX

Collins, Cris cris.collins at gd-ais.com
Tue Jul 6 06:35:01 PDT 2010


Wanted to make sure for the archives that the following questions were 
answered in case others were having similar issues.
All was resolved by using the 4.0 version of syslinux using extlinux.

Ferenc Wagner wrote:
> "Collins, Cris" <cris.collins at gd-ais.com> writes:
>
>   
>> I am trying to boot a ramdisk on a usb stick in read-only mode using
>> extlinux.
>>     
>
> I guess you mean to boot a Linux kernel with an initrd from a read-only
> usb stick.  Right?
>   
Correct.
>   
>> When the system boots all I am getting is a blinking cursor.
>>     
>
> What messages are printed before that?  Beyond the usual BIOS stuff,
> like testing memory and CPU/HDD types.
>
>   
None. Now that it is working I see that I should have been seeing the 
syslinux title and the boot prompt.
>> 1) I partitioned the stick as a linux partition, formated it ext2, and
>> mounted /dev/sda1 on /mnt/flash.
>>     
>
> Did you make the partition active (that is, bootable) in fdisk?
>
>   
Yes.
>> 2) I am running extlinux 3.86.
>> 3) excuted "extlinux -i  /mnt/flash"
>>     
>
> Did it create /mnt/flash/extlinux.sys?
>
>   
Yes.
>> 4) created /mnt/flash/extlinux.conf
>> 5) contents:
>> DEFAULT linux
>> prompt 1
>> timeout 1200
>> LABEL linux
>> KERNEL vmlinuz
>> APPEND initrd=initrd.img rw prompt_ramdisk=0 ramdisk_blocksize=1024
>> ramdisk=2966000 root=/dev/ram0
>> 6) excuted "cat mbr.bin > /dev/sda"
>> 7) copied initrd.img and vmlinuz to /mnt/flash
>> 8) umounted /mnt/flash
>>     
>
> This sounds good.
>
>   
>> I know it sounds strange but I wanted to do the same with isolinux,
>>     
>
> The same?!  Your usb stick is seen by your BIOS either as a HDD (in
> which case the above procedure is correct), as a floppy or as a CD-ROM.
> Isolinux is only applicable in the latter case, but then you mustn't
> partition you usb stick.
>
>   
It was being seen as a hard drive.
>> but get the following error:
>>
>> 16384 ram181(driver?)ext2 iso9660
>> Kernel panic - not syncing: VFS: Unable to mount root fs on
>> unknown-block(1,0)
>>     
>
> This means your kernel was loaded by some means, but I can't imagine
> how.  The bootloader (extlinux or isolinux) should have printed a banner
> and wait for the 120 second timeout or Enter.  Which was it?
>   

isolinux. At this point the project had wanted a bootable DVD and then 
they changed their mind. The problem here had something to do with the 
kernel and was resolved by moving to a 64 bit version of the 2.6.25.14 
kernel compiled using the Cent0S 5.3 2.6.18 config. I just updated the 
the number of ramdisks supported to support the ramdisk size I need. I 
had used the same method to compile the 32 bit version of the 2.6.25.14 
kernel, except had also added the 4 to 64 GB RAM support. I am not sure 
what else I might have needed to do to the 32 configuration to get it to 
work.




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