i'm making a disk(volume) backup/restore system.
i would unmount volume before backup,
but the system volume can not be unmounted.
so the change or access of system volume is worry for me while that system volume is backup.
is it possible that detect which disk sector or ntfs cluster was changed realtime?
that can be filter driver, can it be possible?
So I have a driver that does a child enum on the ACPI PDO. It gets back the methods, and then does an evaluate. There are two ways of doing this, evaluateex and evaluate. Oddly for exactly the same methods they return different data, not different in value, but the ex evaluation data has a 4 byte padding after each package, the eval method doesent. This is for _PSS data.
What is also odd that if the eval is called during IRP_MJ_START_DEVICE the _PCT data is also different to that obtained later on so I assume even then the device hasnt completely started. The _PCT at IRP_MJ_START_DEVICE shows IO port access, but later shows FFHW as the acces.
What is also interesting is that attaching to the PDO outside of AddDevice causes enum children to returns STATUS_NOT_SUPPORTED, which is odd, since the only interface to the PDO is the PDO pointer and the Irp, how DOES the PDO know the Irp is being sent from a DO attached outside of AddDevice? Odd stuff indeed.
Anyway it doesnt affect the functioning of the driver, it controls COU speed OK, but this variability of what the PDO is returning is odd and I cant exmplain it. Anyone have any idea why this is?
First thing, Has you PIC got built in USB hardware or are you trying to do this from basics with I/O lines? If it's the latter, go for the first. If you can't consider finding a USB chip and connecting it to your PIC. Its much much easier to get these things done in hardware than try to do them your self. If you can't do that, consider a PIC with Rs232 and get a USB to Rs232 converter.
Unless you're on the real cutting edge others will have done this before you. It's just a matter of finding them. I remember there are quite a few PIC code sites, though be wary of taking code at face value. I remember seeing a book on coding for USB in my local bookshop a few years ago, which takes, as you request, the developers perspective rather than a protocol specifier's perspective. so have a look.
Obviously you can do this yourself, Its just harder as you already know and you need time, information and patience.
Last Visit: 31-Dec-99 19:00 Last Update: 25-Feb-21 12:55