Re: [edk2-devel] [PATCH v2] MdeModulePkg: Correct high-memory use in NvmExpressDxe

["Tomas Pilar (tpilar)" <quic_tpilar@quicinc.com>]

On 24/02/2022 13:13, Ard Biesheuvel wrote:
> On Thu, 24 Feb 2022 at 13:58, Tomas Pilar (tpilar)
> <quic_tpilar@quicinc.com> wrote:
>> Move the logic that sets EFI_PCI_IO_ATTRIBUTE_DUAL_ADDRESS_CYCLE Pci
>>
>> attribute to DriverBindingStart() before the memory that backs the
>>
>> DMA engine is allocated.
>>
>>
>>
>> This ensures that the DMA-backing memory is not forcibly allocated
>>
>> below 4G in system address map. Otherwise the allocation fails on
>>
>> platforms that do not have any memory below the 4G mark and the drive
>>
>> initialisation fails.
>>
>>
>>
>> Cc: Ray Ni <ray.ni@intel.com>
>>
>> Cc: Ard Biesheuvel <ardb+tianocore@kernel.org>
>>
>> Cc: Leif Lindholm <leif@nuviainc.com>
>>
>> Signed-off-by: Tomas Pilar <quic_tpilar@quicinc.com>
> Ehm, nope, that is not exactly what I meant.
>
> The existing code stores the original PCI attributes in the controller
> private data, enables MMIO/IO decoding and bus mastering, and only
> then sets the dual address cycle attribute.
>
> All of that needs to move, so that the captured attributes are accurate.
>
>
Okay, I was wondering. My thought was that we probably want to re-enable 
bus mastering
on reset so I kept that bit of code in the original location.