RE: [iPAQ] "Dual Boot"

What about taking the approach that BeOS took, as well as one Linux distro I
recall seeing targeting users who run Windows but want to "try Linux" in a
painless way, and have the machine boot into WinCE, then run a small
executable to reboot into Linux? That way, you don't have to hack around in
WinCE. And given that you'd only have to run the program on resets, and
could have it auto-run in WinCE (I think...) it sounds reasonably simple
from a user POV.

-----Original Message-----
From: ipaq-admin@handhelds.org [mailto:ipaq-admin@handhelds.org]On
Behalf Of Dirk van Hennekeler
Sent: Thursday, October 05, 2000 6:13 AM
To: noel@devtech.com
Cc: ipaq@handhelds.org; france@crl.dec.com; jamey@crl.dec.com
Subject: re: [iPAQ] "Dual Boot"

Hi Noel,

Pardon this intrusion on your conversation...

> Jamey,
>
> You seem to be the iPAQ Linux bootloader wizard. And George
> appears to be
> the OSLoader wizard.
>
> And, since you two work for Compaq, and thus have access to
> Pocket PC codes,
> could please explain what it would take to be able to dual
> boot Pocket PC
> (aka Windows CE current edition) or Linux through your
> boatloader? Why not
> be able to dual boot to the OS of one's choice? Perhaps one
> could store a
> copy of the Pocket PC distribution on a CF chip, and boot it
> when one needs
> a Pocket PC application.
Even without the code you can still deduce a lot by looking
at the flash image that you saved a copy of.
Two scenarious come to mind: dedicated Linux handheld which
could boot Windows CE or dedicate Windows CE handheld which
could boot Linux. Where dedicated means the image is in
flash memory.

An initial thought was that the first scenario would be more
difficult. Windows CE is able to execute in place, so moving the
image somewhere else (say a cf card) would likely be a high
risk solution.

The second scenario would be to get in before Windows CE boots
by injecting the bootldr code (that George wrote)
in the boot sequence. It could then determine whether to
continue with the Windows CE boot or boot Linux or
another OS from a cf card. The trick is putting the
bootldr code in the correct place and fixing up the
reset vector to jump to the bootldr first. Potentially this
could all go wrong and it might take more than one iPAQ to
get it right...
With 32MB flash memory it would be simpler. Both OS's could
fit in flash memory.
Assuming you have the 32MB flash memory and the bootldr is in place I
believe it would be a matter of compiling the kernel to use
the correct physical address etc.

I'm not sure how it would be booted from a cf card - that is unfamiliar
territory. At a guess from past posts to this list, the bootldr
would have to be modified to be able to read from the cf card. Once that
is done I guess it would be like booting Linux from a disk.

I like your idea.
You are not alone with this thought, some others on this list
have also suggested this.

>
> What do you think?

> Is this something that you can do? It
Ever thought of chipping in? Now's your chance...:)

> would make the
> jump to handheld Linux a lot safer for a lot more people.

Regards,
Dirk
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Received on Sun Oct 8 21:27:15 2000