DUA on HDD with write filter enabled.

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Guest

Hi All,

I have some questions to ask, anybody please try to answer them:
1. We have XPe system running with DUA for providing software updates
through USB drive. If system boots from HDD and write filter is provided then
how the DUA updates will be provided to the system. If we ensure commit
before shut down then the updates will be provided from next boot event
onwards.
2. If we don’t have a video BIOS then how the system BIOS and XPe will load
the custom made video driver.

Thanks
Roshan.
 
Hello KM,

Much the way the system BIOS provides a set of functions that are used by
software programs to access the system hardware, the video BIOS provides a
set of video-related functions that are used by programs to access the video
hardware. The video BIOS interfaces software to the video chipset in the same
way that the system BIOS does for the system chipset.
We are developing customise solution for our client for that matter we will
have to use different video signal processing cards. I want to know how can i
load the display driver in this case.

Thanks
Roshan.
 
Roshan,

Are you referring to a firmware of the video card?

Anyway, if you are up to use a custom video signal processing card your BIOS (system BIOS) has to allow to pass by the video test
during POST. If that's already the case, XPe part may be easier. If you componentize the driver and have it in your image config,
the system will use it.
I am not totally clear on what's your custom hardware does. But in case it doesn't get enumerated as a video card you may need to
include Headless support components in your image as well.
 
Hello KM,
Thanks for your kind reply, please correct me if I am wrong. During POST the
video test is being carried out with the help of on chip video BIOS. The test
initialize the video adapter, tests the video card and video memory and
display the configuration information on the screen. If we don’t have the on
chip video BIOS (e.g. VESA) the above tests will not be carried out.
We will be using Video card for which we will get the driver from the
vendor. If I componentize the driver and add to my image. I want to know
which boot process will load video driver that will provide us the visible
interface on screen.
Is it the I/O Manager and SMSS (Session Manager Subsystem) that will do the
job of loading the display driver? Same will be the case with Audio driver
also?
Where will I get more information on how the device drivers/application are
loaded by windows XP embedded.

Thanks & Regards
Roshan.
 
Roshan,

XPe is a componentized version of XP Pro. Kernel loads drivers on XPe the same way as it does that on XP Pro.

In other words, if you can make it to work with the driver of the vendor on XP Pro machine, you can make it to work on XPe device.

During boot process there are several components that are making an output to the video channel. Staring from the BIOS (POST
screens) it goes to NT loader (utilizing BIOS calls) switching to graphic mode and transferring control to the kernel. Kernel will
load the actual hardware driver if present and registered, otherwise standard VGA driver is used.

You may certainly want to read Windows DDK documentation for XP. You will find display class driver architecture there with some
good details on the loading order, implementation and interfaces.
 
And I forgot to mention that if the video card doesn't have its own BIOS (I think you referred to this as video BIOS), the main
(system) BIOS will load a default set of video drivers from the motherboard.
That's how it is supposed to work but obviously varies across different mobo implementations.
 
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