[U-Boot] UEFI on u-boot

[Udit Kumar]

> -----Original Message-----
> From: Heinrich Schuchardt [mailto:xypron.glpk at gmx.de]
> Sent: Tuesday, January 16, 2018 12:39 PM
> To: Udit Kumar <udit.kumar at nxp.com>; Alexander Graf <agraf at suse.de>
> Cc: u-boot at lists.denx.de
> Subject: Re: UEFI on u-boot
> 
> On 01/16/2018 06:28 AM, Udit Kumar wrote:
> > Hi Alex,
> >
> >> -----Original Message-----
> >> From: Alexander Graf [mailto:agraf at suse.de]
> >> Sent: Monday, January 15, 2018 5:02 PM
> >> To: Udit Kumar <udit.kumar at nxp.com>
> >> Cc: u-boot at lists.denx.de; Heinrich Schuchardt <xypron.glpk at gmx.de>
> >> Subject: Re: UEFI on u-boot
> >>
> >>
> >>
> >> On 15.01.18 10:32, Udit Kumar wrote:
> >>> Hi Alex
> >>>
> >>>> -----Original Message-----
> >>>> From: Alexander Graf [mailto:agraf at suse.de]
> >>>> Sent: Monday, January 15, 2018 2:45 PM
> >>>> To: Udit Kumar <udit.kumar at nxp.com>
> >>>>
> >>>> Hi Udit,
> >>>>
> >>>> On 15.01.18 10:09, Udit Kumar wrote:
> >>>>> Hi Alex,
> >>>>> Hope you are doing great,
> >>>>>
> >>>>> Could you help on UEFI over the u-boot.
> >>>>> 1- I couldn't locate EFI_DXE_SERVICES in u-boot, do you have plan
> >>>>> to add those
> >>>>
> >>>> Right now the model is that all device drivers are implemented by
> >>>> U-Boot and that only exposes their interfaces to EFI applications.
> >>>> Implementing DXE in U-Boot would open quite a big can of worms, as
> >>>> it would really only be useful in compilation with PI which is a
> >>>> terrible
> >> interface :).
> >>>
> >>> Ok,
> >>>
> >>>>> 2- If I load  a driver (with bootefi) which install few protocols,
> >>>>> is this ok to do with u-boot
> >>>>
> >>>> It depends on how much the driver does, but in general yes.
> >>>> Heinrich is currently working on making the iPXE iSCSI driver work,
> >>>> so his EFI payload would expose an EFI block device to yet another
> >>>> payload running
> >> after his.
> >>>
> >>> Thanks for this,
> >>> Heinrich,  in  this driver, are you accessing underneath hardware
> >>> register by UEFI-Driver and managing UEFI protocols or you are
> >>> relying on some h/w access exposed by u-boot driver
> >>>
> >>>
> >>>
> >>>>> 3- if you say, 2 is ok then I hope these protocols are kept in
> >>>>> some data base, and this new protocol can be opened by an
> >>>>> application
> >>>>
> >>>> Yes, the protocol database is now global and persistent across
> >>>> bootefi invocations.
> >>>
> >>> Thanks
> >>>
> >>>>> 4- if there is some known limitation, like we cannot run
> >>>>> DXE_driver etc
> >>>>
> >>>> What exactly are you trying to do? With the U-Boot UEFI
> >>>> implementation we're trying to find a sweet spot between
> >>>> implementing as much as makes sense, but not the whole UEFI world,
> >>>> as that would just bloat the code needlessly.
> >>>
> >>> I am trying to add a driver (DXE by definition) which
> >>> a) Access the hardware registers. (I said DXE could due to hardware
> >>> registers)
> >>> b) Update memory map as well (AddMemorySpace call)
> >>> c) Finally it export a protocol, which could be used by its test
> application.
> >>>
> >>> For b) I am not able to find function call,
> >>
> >> What exactly beyond efi_allocate_pages() do you need? The EFI memory
> >> map is really only used as data source for EFI applications. The
> >> actual 1:1 U- Boot map is not influenced by it.
> >
> > I am exploring possibility,  If a driver discover memory  and want to add
> this in system.
> > For example,  at build time 1Gb is reserved for a given driver but at
> > run-time driver is told to use little less memory say 512Mb and this
> > driver can return back 512Mb to system (In UEFI call is being
> > AddMemorySpace under DXE services)
> >
> 
> The UEFI specification defines different memory types which can be used
> when allocating memory. Whether a memory type can be used by an UEFI OS
> loader or an OS determines on the boottime exit event. Many classes of
> memory become generally available after exiting the boottime. This is
> decribed in chapter "7.2 Memory Allocation Services" of UEFI spec 2.7.

For allocation this is perfectly fine. How a driver can update the memory 
map. 
Let me ask this in other way, when we create UEFI memory map in u-boot 
How we are creating this ? using memory node of device tree or some other 
way.

Thanks
Udit 



> Regards
> 
> Heinrich
> 
> >
> >>> For a), if I say driver is UEFI and accessing hardware register,
> >>> will this be
> >> acceptable ?
> >>
> >> Yes, definitely. All you'd need to do is set the efi application type
> >> to application, then register your protocols and access hardware
> >> registers using direct MMIO access to their respective regions.
> >
> > Thanks
> >
> >>
> >> Alex