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link Multiple FDOs for a Single PDO ?
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  Message 1 of 7  
17 Aug 00 17:25
ntdev member 2482
xxxxxx@usa.net
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Multiple FDOs for a Single PDO ?
Hello, Is it possible for a SINGLE PhysicalDeviceObject to have MULTIPLE (more than just 1) FunctionalDeviceObjects on top of it ? Basically I have a device A which has three different functionalities (F1, F2 and F3), and I want to create a separate DeviceObject for each functionality of the device, so that the user can access each functionality separately. How can I achieve this: 1. Can I have ONE PDO for Device A; ONE FDO for F1, SECOND FDO for F2 and THIRD FDO for F3 ? OR 2. Do I need THREE PDOs for Device A (one each for F1, F2 and F3); Corresponding FDOs (ONE for F1, SECOND for F2 and THIRD for F3) ? And if its #1, do I just call IoCreateDevice() multiple times in my AddDevice() ? Is there any relevant example ? Any information or pointers are appreciated. Thanks much, Puja
  Message 2 of 7  
17 Aug 00 17:47
ntdev member 2716
xxxxxx@hotmail.com
Join Date: 25 May 2000
Posts To This List: 58
Re: Multiple FDOs for a Single PDO ?
you cannot have 3 fdos over 1 pdo. this limitation I believe is imposed because otherwise the Pnp manager will not know to which fdo the pnp calls are to be routed. you have 2 alternatives 1. make 1 fdo and the other 2 filter DOs 2. make 3 pdos and corresponding fdos. regards jeseem mailto:xxxxx@hotmail.com http://www.nesttech.com ----- Original Message ----- From: <xxxxx@usa.net> To: "NT Developers Interest List" <xxxxx@lists.osr.com> Sent: Thursday, August 17, 2000 5:21 PM Subject: [ntdev] Multiple FDOs for a Single PDO ? > Hello, > > Is it possible for a SINGLE PhysicalDeviceObject to have MULTIPLE (more > than just 1) FunctionalDeviceObjects on top of it ? > > Basically I have a device A which has three different functionalities (F1, > F2 and F3), and I want to create a separate DeviceObject for each > functionality of the device, so that the user can access each functionality > separately. How can I achieve this: > > 1. Can I have ONE PDO for Device A; ONE FDO for F1, SECOND FDO for F2 and > THIRD FDO for F3 ? > > OR > > 2. Do I need THREE PDOs for Device A (one each for F1, F2 and F3); > Corresponding FDOs (ONE for F1, SECOND for F2 and THIRD for F3) ? > <...excess quoted lines suppressed...>
  Message 3 of 7  
17 Aug 00 19:03
ntdev member 2482
xxxxxx@usa.net
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Re: Multiple FDOs for a Single PDO ?
Hello, I noticed in the OSR Device Driver Book, Chapter 9, Page 178, there is a mention of multiple Device Objects, but since it is for WinNT and not Win 2K, it doesn't distinguish between PDOs and FDOs. I would think that it is referring to the FDO (since it is the Function/Device Driver that it is talking about). Am I correct ? Also, if we can have multiple FDOs, then they should be possible on a sin gle PDO (because otherwise doesn't it mean that we would have to modify the corresponding Bus Driver to create multiple PDOs for the device it enumer ates, and my understanding is that Bus Drivers are standard). Is this correct ? Thanks for your help. Thanks Puja > -----Original Message----- > From: xxxxx@lists.osr.com > [mailto:xxxxx@lists.osr.com]On Behalf Of Jeseem > Sent: Thursday, August 17, 2000 2:42 PM > To: NT Developers Interest List > Subject: [ntdev] Re: Multiple FDOs for a Single PDO ? > > <...excess quoted lines suppressed...> will > not know to which fdo the pnp calls are to be routed. > > you have 2 alternatives > 1. make 1 fdo and the other 2 filter DOs > 2. make 3 pdos and corresponding fdos. > > regards > jeseem re > > than just 1) FunctionalDeviceObjects on top of it ? > > > > Basically I have a device A which has three different functionalities (F1, > > F2 and F3), and I want to create a separate DeviceObject for each > > functionality of the device, so that the user can access each > functionality > > separately. How can I achieve this: > > > > 1. Can I have ONE PDO for Device A; ONE FDO for F1, SECOND FDO for F2 and > > THIRD FDO for F3 ? > > > > OR > > > > 2. Do I need THREE PDOs for Device A (one each for F1, F2 and F3); > > Corresponding FDOs (ONE for F1, SECOND for F2 and THIRD for F3) ? > > > > And if its #1, do I just call IoCreateDevice() multiple times in my > > AddDevice() ? > > ____________________________________________________________________ Get free email and a permanent address at http://www.amexmail.com/?A=1
  Message 4 of 7  
17 Aug 00 21:06
Mark Roddy
xxxxxx@hollistech.com
Join Date: 25 Feb 2000
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Re: Multiple FDOs for a Single PDO ?
> > I noticed in the OSR Device Driver Book, Chapter 9, Page 178, there is a > mention of multiple Device Objects, but since it is for WinNT and > not Win2K, > it doesn't distinguish between PDOs and FDOs. I would think that it is > referring to the FDO (since it is the Function/Device Driver that it is > talking about). Am I correct ? > There is nothing equivalent in NT4 to the PDO-FDO relationship in W2K. How a driver chose to represent IO paths using device objects was entirely up to each driver, or each stack of related drivers. > Also, if we can have multiple FDOs, then they should be possible > on a single > PDO (because otherwise doesn't it mean that we would have to modify the > corresponding Bus Driver to create multiple PDOs for the device > it enumerates, > and my understanding is that Bus Drivers are standard). Is this correct ? > > You really can't have multiple FDOs for a PDO. Each PDO has a PnP enumeration ID, and the PnP manager uses that ID to select a single Driver as the target for an AddDevice operation. Now of course in your AddDevice routine you could create all sorts of device objects for whatever reason you desire, but only the one attached to the PDO is going to be within the PnP architecture. If you really want to have several IO targets represented as device objects, then the PnP/WDM way to do this is to create an abstract IO bus and treat the FDO of the original PDO as a bus driver FDO and have it respond to bus enumeration requests and have it create new PDOs for its bus, and have drivers registered as the function drivers for these new PDOs. See the toaster bus driver for some clues as to how this can be done. Note that there is nothing other than increased complexity that prevents you from having a single driver module that is the bus driver for the original FDO, and the function driver for each of your enumerated PDOs. See for example what the disk class driver (and the classpnp library) is doing to create an abstract bus at the disk level.
  Message 5 of 7  
21 Aug 00 19:09
ntdev member 2482
xxxxxx@usa.net
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Re: Multiple FDOs for a Single PDO ?
Thanks for the explanation, Mark. I do have one question: would the FDO of the original PDO (in your example below) be connected to the new PDOs above it ? Or would these stacks be totally independent of each-other ? The DDK and Walter Oney's book (Pg 23, Fig 2.2) show a link between these two. Would the IRPs be passed down via this link to the lower Driver ? Thanks for the clarification. Puja > If you really want to have several IO targets represented as device objects, > then the PnP/WDM way to do this is to create an abstract IO bus and treat > the FDO of the original PDO as a bus driver FDO and have it respond to bus > enumeration requests and have it create new PDOs for its bus, and have > drivers registered as the function drivers for these new PDOs. See the > toaster bus driver for some clues as to how this can be done. Note that > there is nothing other than increased complexity that prevents you from > having a single driver module that is the bus driver for the original FDO, <...excess quoted lines suppressed...>
  Message 6 of 7  
21 Aug 00 20:28
ntdev member 2482
xxxxxx@usa.net
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Re: Multiple FDOs for a Single PDO ?
I think I found an answer to my question further down in Walter Oney's book, with examples! Thanks anyway, Puja On 08/21/00, "xxxxx@usa.net" wrote: > Thanks for the explanation, Mark. I do have one question: would the FDO of the original PDO (in your example below) be connected to the new PDOs above it ? Or would these stacks be totally independent of each-other ? The DDK and Walter Oney's book (Pg 23, Fig 2.2) show a link between these two. Would the IRPs be passed down via this link to the lower Driver ? Thanks for the clarification. Puja
  Message 7 of 7  
21 Aug 00 22:15
Mark Roddy
xxxxxx@hollistech.com
Join Date: 25 Feb 2000
Posts To This List: 2663
Re: Multiple FDOs for a Single PDO ?
> > > > Thanks for the explanation, Mark. I do have one question: would > the FDO of > the original PDO (in your example below) be connected to the new > PDOs above > it ? Or would these stacks be totally independent of each-other ? > It does get confusing. We have two flavors of PDOs and two flavors of FDOs. Lets call PDO-1 the PDO created by some other bus driver (a hardware bus driver in your case, but that doesn't matter.) Your driver is regestered as the function driver for whatever the PnP ID of PDO-1 is. When a PDO-1 is enumerated your driver is loaded if required and called at your AddDevice interface with a pointer to an instance of a PDO-1 device object. You create an FDO (which we will refer to as an FDO-1 FDO.) You attach your FDO-1 device object and we now have a stack like so: FDO-1 | | Driver 2 ------------- | | Driver 1 PDO-1 There is a direct device object relationship between FDO-1 and PDO-1. FDO-1 is on the linked list of attached devices that exists in the PDO-1 device object. Some time later your bus driver role in your driver enumerates three PDOs, all of them type PDO-2 (they could actually be different PnP types, as in PDO-2a PDO-2b PDO-2c but that is way too complicated for now and changes nothing relevent.) The relationship between FDO-1 and its enumerated PDO-2 device objects is NOT a direct stacking relationship as in the relationship between FDO-1 and PDO-1. Instead the picture looks something like this: FDO-2 FDO-2 FDO-2 | | | | Driver 3 | | ------------------------------------ | | | FDO-1 | | | | PDO-2 PDO-2 PDO-2 | Driver 2 ------------------------------- | | Driver 1 PDO-1 PDO-2 is not 'attached' or 'stacked' above FDO-1 or PDO-1. If an IRP is passed from a PDO02 pdo to FDO-1 (and from there to PDO-1) that is a function of an internal design of Driver-2 and not part of the Wdm design. Whatever driver is registered as the function driver for PDO-2 pdos has its own FDO-2 type FDOs attached above your PDO-2 pdos, just as your FDO-1 fdo is attached above some other driver's PDO-1 pdo. This can of course recurse again in driver3 as each FDO-2 fdo could function as a bus driver fdo and create its own set of PDOs (PDO-3 pdos.) It is also quite possible that the FDO-2 fdos are in fact created by Driver-2 as Driver-2 could register as the function driver for both PDO-1 pdos and PDO-2 pdos. > The DDK and Walter Oney's book (Pg 23, Fig 2.2) show a link between these > two. The illustration is unclear about what the arrows mean. I think that walter means that there is "a relationship" shown by the arrows, without defining what that relationship is or if it is always the same for any arrow connecting any box. The relationship between a bus driver FDO (FDO-1 above) and its enumerated PDO(s) (PDO-2 above) is a parent/child relationship. The PnP manager understands that all the PDO-2s in the picture above 'belong to' FDO-1 because FDO-1 built a reply to an IRP_MN_QUERY_DEVICE_RELATIONS pnp IRP of subtype BusRelations that listed each of these three PDOs. Other than this, there is no PnP architected connection between each PDO-2 and its enumerating FDO.
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