Hi All, My upperfilter driver cause crash in ks.sys, when it works with another filter driver(but both filter drivers work fine when working alone with the audio driver) The situation is everytime the filter driver generates an Irp call, like KS_STREAM_WRITE or KSPROPERTY_CONNECTION_STATE then it crashes in ks.sys. It does normally call to my driver->portcls->ks.sys, and then cause a PAGE_FAULT_IN_NONPAGED_AREA (50) error at ks!KsDispatchIrp+0x126. Having no idea on the problem, I found there's something called ks debug extension that I might make some use of. First I tried debug build XP+debug SP2, but it doesn't install normal kb888111. Then I tried to copy ks.sys, portcls.sys, kmixer.sys to normal xp, but it doesn't work like the document described. Here are some examples: kd> !ks.libexts details LibExt Details: -------------------------------------------------- LibExt "STREAM!" : Status : ACTIVE This is the stream class library extension to the KS DLL. It supports dumping device extensions, filters, streams, and SRBs. Hooks : dump enumdevobj graph automation You can see there's no portcls or kmixer debug exports. kd> !ks.dumplog Start [Irp 00000000 / Frame 00000000] @ 001d6c62f [Graph = 00000000, Filter = 00000000, Pin = 00000000, Component = 00000000 It's the only log it prints, nothing else at all. The windbg version is 6.6.7.5, target windows version is WinXP SP2, with a HDAudio driver installed on it. Is this because the checked build ks.sys on XPSP2 are actually stripped down? or I miss anything here? Thanks if anyone can give me some hint. Regards, priv ****************** WDMAUDIODEV addresses: Post message: mailto:wdmaudiodev@xxxxxxxxxxxxx Subscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=subscribe Unsubscribe: mailto:wdmaudiodev-request@xxxxxxxxxxxxx?subject=unsubscribe Moderator: mailto:wdmaudiodev-moderators@xxxxxxxxxxxxx URL to WDMAUDIODEV page: http://www.wdmaudiodev.com/