Re: FmpDeviceLib

["Kinney, Michael D" <michael.d.kinney@intel.com>]

Tom,

Thanks for noticing this issue.  I need a little 
time to evaluate this use case and see what changes
are required to make this work for a UEFI driver
that manages many controllers.

Thanks,

Mike

> -----Original Message-----
> From: edk2-devel [mailto:edk2-devel-
> bounces@lists.01.org] On Behalf Of Tomas Pilar (tpilar)
> Sent: Tuesday, November 27, 2018 7:29 AM
> To: Gao, Liming <liming.gao@intel.com>; edk2-
> devel@lists.01.org
> Subject: Re: [edk2] FmpDeviceLib
> 
> Okay, so I just noticed that FmpDxe is full of module
> globals including the image descriptor, so it
> necessarily requires that the driver that includes it as
> a library can only ever control one controller.
> 
> Cheers,
> Tom
> 
> On 27/11/2018 15:23, Tomas Pilar (tpilar) wrote:
> >
> > On 27/11/2018 14:33, Gao, Liming wrote:
> >> Tom:
> >>   FmpDeviceLib can use UEFI driver model/driver
> binding protocol so it can install FMP on its device
> handle during the BDS/Device connection phase. It can
> implement RegisterFmpInstaller() to install FMP protocol
> in its device handle. In this way, FmpDeviceLib is like
> UEFI driver with UEFI driver binding protocol.
> >>
> >> Thanks
> >> Liming
> > Hi Liming,
> >
> > Sure, so now I can install FMP onto my
> ControllerHandle. Say that someone gets the FMP and
> calls GetImageSize. The FmpDxeLib does some checks and
> then it calls FmpDeviceLibGetImageSize() with no context
> parameter. This method is supposed to be implemented by
> me, the driver writer, but how is the code in this
> method meant to know which Controller are we getting the
> image size from?
> >
> > So maybe I can define some module globals, declare
> them in a cross include file, include that in my driver
> and and have the driver populate the module globals
> during probe. This immediately limits the usefulness by
> requiring that each driver only ever drives one
> controller.
> >
> > And then you consider how to do a SetImage without
> being even given the Handle of the Controller. Do you
> stuff the controller handle into a module global
> parameter that gets populated during the BDS phase?
> >
> > I guess you could enumerate all FMP instances, see
> which one of them advertises your ImageTypeId and get
> the handle that the FMP is installed on that way. But
> that seems rather insane and would cause issues if you
> have two of the same device in the platform, unless you
> check the HardwareInstance as well? This seems insane.
> >
> > Cheers,
> > Tom
> >
> >>> -----Original Message-----
> >>> From: edk2-devel [mailto:edk2-devel-
> bounces@lists.01.org] On Behalf Of Tomas Pilar (tpilar)
> >>> Sent: Tuesday, November 27, 2018 9:26 PM
> >>> To: edk2-devel@lists.01.org
> >>> Subject: [edk2] FmpDeviceLib
> >>>
> >>> Hi all,
> >>>
> >>> I am looking at using FmpDxeLib so I need to
> implement the FmpDeviceLib. However, it seems like the
> library functions do not take any
> >>> private struct as a parameter, so I am struggling to
> figure out how to read information off the hardware.
> FmpDxe does not even pass its
> >>> created protocol instance when calling the library
> functions, leading me to believe that the only way to do
> this is to assign a pointer to
> >>> private struct during library construction, but that
> means that a driver that uses the code can only ever
> service a single controller.
> >>>
> >>> Can you offer any insights?
> >>>
> >>> Cheers,
> >>> Tom
> >>> _______________________________________________
> >>> edk2-devel mailing list
> >>> edk2-devel@lists.01.org
> >>> https://lists.01.org/mailman/listinfo/edk2-devel
> 
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