[U-Boot] UEFI on u-boot

[Alexander Graf]

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.

> 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.


Alex