1. File System and File System Filter Ecosystem Update Neal Christiansen Development Lead File System Filter Team

2. BOOT.INI and Longhorn • The boot.ini file is no longer used to configure boot parameters. • New BCD (boot configuration data) file • Implemented as a registry hive • Resides in \boot\bcd • There is a new tool called bcdedit which is used to configure options • Boot.ini is still used for downlevel operating systems if you are booting multiple OS’s on the same system

3. Useful bcdedit commands • bcdedit –enum • List current settings • bcdedit –enum all • List all settings • bcdedit /? • Basic help • bcdedit /? Types • Lists the bulk of the settings

4. Useful bcdedit commands • Enable debugging • bcdedit -debug on • Followed by one of the following: • bcdedit -dbgsettings serial debugport:1 baudrate:115200 • bcdedit -dbgsettings 1394 CHANNEL:32 • bcdedit –dbgsettings USB TARGETNAME=U1

5. Doing IO from Completion Routines • Many of you issue IO operations from IO Completion routines (or post-operation callbacks) when those routines are at an IRQL level lower then DPC level • Filter manager promoted this with routines like FltDoCompletionProcessingWhenSafe

6. Doing IO from Completion Routines • We have determined that it is not safe to ever perform any operation in a completion (or post-operation) callback routine regardless of your current IRQL level • We have been seeing deadlock with various storage drivers because of this • The most common scenario we have seen is when using dynamic disks with RAID enabled • We have seen it with other drivers as well • Consider this a new “rule for filters”

7. Doing IO from Completion Routines • It is our very strong recommendation that you modify your existing products across all OS’s to stop doing this • You have two options: • If the operation is synchronous you should synchronize back to your dispatch routine • Use IoIsOperationSynchronous • If the operation is asynchronous you should queue the request to a worker thread • You may have to throttle your worker thread usage because you can cause deadlocks if you consume all of the worker threads

8. Doing IO from Completion Routines • What is filter manager going to do about this? • FltDoCompletionProcessingWhenSafe will be modified to either queue the request or automatically synchronize and call the specified routine. • This will happen automatically so if you use the current routine you should not have to change anything • We are going to modify the minifilter verifier to detect this situation and break