Re: x86 romboot vs BIOS

1. Port CE5 romloader to CE6

Yes, I would think that this would be possible.

2. Add more functionality to BIOSLOADER. (download from ethernet is
one)
- Is this possible? I've heard that modifying the biosloader
code and
rebuilding it would make is unusable?

I don't understand why you would want Ethernet download in your normal
production bootloader. Is the end user going to remote boot the thing over
the network? Not very responsive during boot!

3. Be able to boot a second CE image when already inside CE without
rebooting
- LoadCEPC uses himem.sys to access XMS. Anyone tried to do
something similar inside WinCE?

Since Windows CE is running in flat 32-bit mode, you don't have to do
*anything* to access extended memory. There is no extended memory. It's
just flat 32-bit address space.

Anyway, it's time to talk to the customer and discuss what makes sense,
rather than a random collection of "it could do that" statements. Find out
*what* they need, now *how* they've decided you should do it. What does
"safe boot" mean? It's an industrial controller! How often is it going to
be rebooted? Why would you want to be able to interrupt a boot of an
industrial controller? That seems like the *last* thing you'd want to do.

As for updating nk.bin, you should already see how that could be done easily
with no bootloader involvement at all. nk.bin is on some storage media.
The bootloader loads it from there to RAM and jumps to it, as fast as it
damn well can (!) When you want to update nk.bin, since the version on the
storage media is *not in use* once the bootloader is done with it, you can
download a new version from the Web, via FTP, copy it from a plug in hard
disk or flash drive or whatever you want to do. The next time you boot the
unit, bingo, you get the new OS. Simple, easy to implement (the hardest
thing is making the bootloader understand how to get nk.bin from the storage
media), easy to update, flexible, etc.

Paul T.


On 6 Feb, 00:14, "Paul G. Tobey [eMVP]" <p space tobey no spam AT no
instrument no spam DOT com> wrote:




Yes, your understanding of what the bootloader/romloader does. No,
however,
it's not really normal to just put the OS in ROM.

We have some x86 designs and they place the bootloader in the normal
reset
vector location. They then load the nk.bin file from storage media to
RAM
and jump to it after changing the processor mode, testing everything,
etc.
Doing some sort of direct jump to the OS with the reset vector isn't
really
the way things were designed to work so, if you try to do that, you're
pretty much on your own. Somehow, you'd have to assure that the
processor
is in the right mode, etc. somewhere early in the process. Windows CE
assumes that your 32-bit processor is running that way on entry and, in
the
case of the reset vector, the processor would be running in real mode.
I
guess that you might be able to put the code to fix up the processor in
the
OS startup code, but I've never seen the advantage of that.

Further, you then have to worry about how you get a huge nk.bin image
to a
location in your device that makes sense. The reset vector on x86 is
0xf000:0x0000 (you remember segment:offset addressing, right? ;-) That
means that you have to place enough ROM starting at that location to
hold
your nk.bin when it's addressed linearly. I suppose that it's
possible, but
the x86 wasn't really designed to do that, so again you're on the edge
of
you-can-do-anything-with-enough-time-and-money space.

Paul T.- Skjul sitert tekst -

- Vis sitert tekst -



.

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