Removable disk and IRP_MN_QUERY_CAPABILITIES

NTDEV
1

Hello folks,

My upper filter for disk drives does IRP_MN_QUERY_CAPABILITIES during AddDevice, to know whether the disk is removable or not. This works most of the time, but sometimes when I plug some USB pen drive, the “removable” flag in DEVICE_CAPABILITIES is not set.

At first I thought it could be my mistake, but devmgmt doesn’t show the CM_DEVCAP_REMOVABLE either. It doesn’t happen all the time though.

I think it’s safe to query capabilities during AddDevice, isn’t it? If yes, any ideas about what could be the problem?

Thanks guys.

2

Is it happened in the same hardware? It could be possible that a driver for this hardware contains a bug. Usually, not always so, this flag set up by hardware driver.

Igor Sharovar

3

Yes, it has happened with the same hardware that worked a couple of hours ago :-\

4

BTW, if it helps, suddendly my breakpoints don’t trigger Windbg…

5

I think it’s my mistake.

I was gettint the CM_DEVCAP_REMOVABLE flag when filtering the usb class, and I guess CM_DEVCAP_REMOVABLE is never set for the “disk drive” class, am I right?