Oh James,
these answers are much out of concept.
James Richard Tyrer wrote:
Ing. Daniel Rozsnyó wrote:
<SNIP>
You can obtain a unique IP for the PC side using DHCP.
DHCP wouldn't be started till after the OS was booted, so that isn't
going to work.
Why run it on PC? The usual network setup for DHPC (one segment):
PC
- dhcp client for EV interface
EV
- dhcp client
ROUTER
- dhcp server for LAN
- wan to the Internet
Here the question is how to detect which IP is of the EV. It can be by
scanning the network, magic packets, uPNP...
If you have 2 network cards in the PC, then the link to EV is dedicated:
EV
- static ip
PC
- static ip for EV interface
- dhcp client internet interface
ROUTER
- dhcp server for LAN
- wan to the Internet
You set the IP for EV in the firmware build (default) and later you can
change it over network / serial / usb / IR remote.
Also if you have two routers, the second one can provide a dynamic IP
for the second segment (the PC-EV link). When you merge the DHCP server
to the EV box, you can run the display on dedicated link without
configuration.
NOTE: If you have more NIC's in the PC, the "BIOS extension ROM for VGA
emulation for EV" has to know some way which NIC to use. Probably the
supported one, or in case of multiple supported NIC's it will have to
try all the interfaces and look for an alive EV box.
You can discover the display devices IP either by scanning the
network, or sending a broadcast "magic" packet (our own discovery
protocol, or maybe a standard way - uPnP protocol should be for this
kind of stuff).
As I think I said, you could have the card that was emulating VGA
respond to 127.0.0.x.
VGA does not go thru IP :)
VGA is a set of BIOS calls (+ memory area + io registers).
Anyway, you can't take IP addresses of 127.0.0.x out of your computer as
127.0.0.0/8 is handled by 'lo' driver. At least here on my Windows
laptop, I assume Linux do the same. This is basic networking setup.
The PC side emulates a video card.
Actually not. The BIOS provides the standard VGA interrupt routines.
How the hardware handles this isn't really relevant.
Actually yes. The PC side is by minimalistic view only a BIOS extension
code ROM, with not that minimal look, you count in a supported NIC:
You need to make 2 devices for the above:
First is sitting as an independent node on the Ethernet, and can do X
and video decoding [the original goal of this list].
The second thing is a NIC+BIOS add-on card for PCI/PCIE, which
emulates a VGA card/keyboard/mouse. Who wants to boot or install his
PC over ethernet buys this card, otherwise it will be not required, as
the kernel loads and networking is up, you can access the other box
the same way.
You could make such a card. However, as I said, there are VGA BIOS
routines which are in the BIOS on the video card for booting. After you
boot an OS, you are going to be using a driver for that OS. The only
problem is that running DOS would be limited to using the BIOS routines
-- probably not a great concern anymore.
So you agree now with the above.
BTW: The support to transfer the BOOT image to the EV box is only needed
if you can provide also back-channel communication for HID (at least
keyboard), which can be used to configure the BIOS, editing via GRUB
loader, resolving root mount point issues with certain initrd..
Otherwise nobody needs to know about the PC's boot, if he/she can do
nothing about it and has to go to the console.
BTW: is it possible for the X box to open a new window when some PC
boots up and display its console?
Basically, no. It would have to start X for this to happen. Since the
boot mode uses only the VGA BIOS routines to directly access the
hardware this wouldn't work.
Hey, that is bad concept! Why you want to run a video-transfer driver
and on top of that the X, if you can run the X directly on the target?
So if the box runs the X server, the BIOS extension will contain a X
client (assuming underlying networking is up and running) and then you
can pop up a boot image on the target device. Using X protocol.
This way you could make a setup which does not use our special hw X
box, but a normal PC with X
After you boot and are running X, that is possible.
What is running on the EV box is not the concern of what is installed on
the PC. It is a separate, stand-alone node on ethernet.
and when you equip your servers with the NIC/BIOS add-on, you get a
KVM like thing.
What do you say?
You can't run X (communicate with an X terminal) until after you boot
the OS and start X or an X compatible thin client system.
The EV will implement an X server if it has a processor. It is an old
technology, so today you should be able to implement it using a 8 bit
microcontroller :)
D.
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