Moin Patrick,

18.02.97 21:13, you wrote a message to Mike Bilow:

 PH> [..]
 MB>> The closest you can come to accomplishing this is to have the
 MB>> driver allocate some memory with DevHelp_VMAlloc() and then make
 MB>> it visible in process address space with
 MB>> DevHelp_VMGlobalToProcess().  
 PH> How can I go the other way round ?

 PH> Application allocates a memory buffer in process space and issues
 PH> an ioctl() passing that pointer to my driver. How has that passed
 PH> address to be converted so the driver can fill my application's
 PH> buffer ?

The system converts the 0:32 pointer passed to DosDevIOCtl to a 16:16
pointer usable during the ioctl.  Pointers inside that datapacket (pointer
to pointer, ugly) have to be translated by the driver.
If data has to be accessable at any time it has to be locked, a GDT
selector has to be allocted and mapped.
Any databuffer should be checked via DevHelp_VerifyAccess.

C-x C-s
    Vitus [Team OS/2 Germany #835]

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