Re: Multiple boot from USB stick

[Karsten Malcher]

Hello Andrei,

Am 16.02.2016 um 10:48 schrieb Andrei Borzenkov:
> On Tue, Feb 16, 2016 at 12:37 PM, Karsten Malcher
> <address@hidden> wrote:
>>> linux16 /memdisk iso
>>> initrd16 /fdbase.iso
>>> boot
>>>
>>> Does it suite as a concrete solution? :)
>>>
>> I was talking about the file FreeDOS_1.1.iso.
>> Where did you get this 2 iso files?
> There is one iso file. Sorry, it was 1.0, not 1.1:
>
> http://www.freedos.org/download/download/fdbasecd.iso

O.K. This is clear now.
One more interesting thing. When you use

http://www.freedos.org/download/download

you can get here:
http://www.ibiblio.org/pub/micro/pc-stuff/freedos/files/distributions/


But for me still is not clear where you get the memdisk.iso and fdbase.iso ?

>
>> Why you can boot them without a loopback?
>>
> Because no loopback is needed. I want to boot from ISO, not extract
> files from it.

I thought grub must use loopback to access the kernel to boot within an iso 
file?

>
>> But this method is working now and i can understand why:
>> menuentry "FreeDOS ISO Image Isolinux" {
>>         set isofile="/boot/iso/FreeDOS_1.1.iso"
>>         loopback loop (hd0,1)$isofile
>>         linux16 (loop)/ISOLINUX/MEMDISK
>>         initrd16 (loop)/ISOLINUX/FDBOOT.IMG
>> }
> I do not know what fdboot.img does so I cannot comment.

This is the kernel image of freedos within the iso file.

>
>> With use of loopback i am mounting the iso file.
>> Then both files within the iso are loaded and executed.
>>
>> FreeDOS 1.1 is starting, but then it can't work with the files within the 
>> ISO.
>> So i get the message: "SETUP wasn't able to locate any disks to install 
>> FreeDOS 1.1 from"
>>
> Well, I did not try to launch setup, but I can access ISO after
> manually loading eltorito.sys and shu-bla-bla (whatever name for CD
> shim is, do not remember).

I think there are parts of your grub.cfg missing.
So i can't follow you.

> But I am not surprised it does not work for you. I suspect fdboot.img
> contains just enough of FreeDOS to locate and access CDROM. But with
> the way you boot it there is no CDROM anywhere. The way I boot CDROM
> access is emulated by memdisk.

The role of memdisk is still not clear for me.
But it does what i expected from it:
http://www.syslinux.org/wiki/index.php/MEMDISK

Freedos can't access the files within the iso, because the iso file is not 
"mounted as cdrom".
I have no idea how to do the trick?

Cheers
Karsten