Static and Dynamic Enumeration
uba
I'm understanding static and dynamic child bus enumeration in KMDF.
When I plug-in a USB mass storage device to a PC, I see two devices
being shown in device manager, one under "Universal Serial Bus
Controllers" and other under "Disk Drives".
Is this an example for static child enumeration or dynamic child
enumeration?
Is the device under "Universal Serial Bus Controllers" a software bus
driver?
Do i need to have a software bus driver to enumerate a child device as
either static or dynamic?
I'm new to KMDF. Pardon me if the question sounds silly.
Thank You,
kid
Don Burn
happens what is going to be created in the way of devices. In some cases a
bus driver knows it needs specific devices, for instance a single controller
that does two functions may need to split those functions in all cases, that
is a static enumeration.
If you are new to KMDF then you probably do not need to do a bus driver.
You should concentrate on function drivers and filter drivers since that is
the bulk of the drivers.
--
Don Burn (MVP, Windows DKD)
Windows Filesystem and Driver Consulting
Website: http://www.windrvr.com
Blog: http://msmvps.com/blogs/WinDrvr
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uba
> The USB example is a dynamic enumeration, you don't know until something
> happens what is going to be created in the way of devices. In some cases a
> bus driver knows it needs specific devices, for instance a single controller
> that does two functions may need to split those functions in all cases, that
> is a static enumeration.
>
Thank you for the quick reply.
So USB mass storage (Pen drive/USB Stick) is an example for dynamic
enumeration.
I have a USB memory card reader which supports SD/MS flash media. When
i plug-in the card reader I get two drives in windows explorer (say D:
\ and E:\). When i insert SD card device is detected. I think this is
an example for static enumeration.
USB Mass Storage (Pen drive/USB Stick) - Dynamic Enumeration
USB Memory Card Reader (SD/MS) - Static Enumeration
Please correct me if I'm wrong.
Thank You,
kid
Don Burn
devices will be plugged in, so when a device is plugged in it checks the
bus, reads the devices descriptor, and DYNAMICALLY creates the device
object.
For an example of static, say you had a PCI device that had a set of
registers all mixed together that was both a serial port and a network port
and only one of each. When the driver for that PCI device is loaded, it
knows that it needs to create a physical device object for a custom serial
port and for a custom network network interface controller, so it can
STATICALLY allocate these since the presence of the underlying PCI device
ensures these are going to be there.
--
Don Burn (MVP, Windows DKD)
Windows Filesystem and Driver Consulting
Website: http://www.windrvr.com
Blog: http://msmvps.com/blogs/WinDrvr
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uba
> No they are all dynamic enumeration. The USB bus drivers have no idea what
> devices will be plugged in, so when a device is plugged in it checks the
> bus, reads the devices descriptor, and DYNAMICALLY creates the device
> object.
>
Thank you for the reply.
I have one question here. Is the software bus driver optional to
create any child device?
Like in a USB mass storage device, I assume usbstor.sys (PDO) is a
software bus driver and disk.sys (FDO) is the dynamic child device. Is
this correct???
Regards,
kid