Re: [PATCH 0/5] ArmPkg et al: remove UncachedMemoryallocationLib

[Ard Biesheuvel <ard.biesheuvel@linaro.org>]

On 29 August 2017 at 16:47, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote:
> On 29 August 2017 at 16:44, Leif Lindholm <leif.lindholm@linaro.org> wrote:
>> On Fri, Aug 25, 2017 at 01:10:09PM +0100, Ard Biesheuvel wrote:
>>> This series is a followup to 'ArmPkg/ArmDmaLib: remove dependency on
>>> UncachedMemoryAllocationLib' sent out yesterday, and removes library
>>> entirely.
>>>
>>> There are two reasons for this:
>>> - UncachedMemoryAllocationLib is often abused by drivers that should
>>>   be using DMA abstractions instead. It is up to the platform to decide
>>>   whether DMA is cache coherent or not, and the fact that non-cache
>>>   coherent DMA may be implemented using uncached allocations should remain
>>>   an implementation detail of the DmaLib instance.
>>>
>>> - The code is poorly maintained, only frees its allocations in the destructor,
>>>   and misleads by exposing pool allocate/free entry points that are actually
>>>   backed by page based allocations.
>>>
>>> Patches #1 and #2 add a DmaAllocateAlignedBuffer() to DmaLib and both
>>> its implementations. This is required for current users of
>>> UncachedMemoryAllocationLib that rely on minimum alignment to be able
>>> to switch the DmaLib.
>>>
>>> Patches #3 and #4 remove a couple of stale references.
>>>
>>> Patch #5 actually removes the library and its single remaining implementation.
>>
>> For the series:
>> Reviewed-by: Leif Lindholm <leif.lindholm@linaro.org>
>>
>> However, this breaks a bunch of (edk2-)platforms: juno, fvp, tc2,
>> hikey and armada70x0. Is there a follow-on patch coming for those,
>> and could you hold off on pushing this series until that is ready?
>>
>> Armada has the only non-bogus UncachedMemoryAllocationLib dependency,
>> the others are just trivial deletions.
>>
>
> Yes. There are interdependencies between repos, so I will just merge
> #1 and #2 and hold off with the rest until after all dependencies have
> been removed.


Patches #1 .. #4 pushed as

deef290f95e0 EmbeddedPkg/DmaLib: add routine to allocate aligned buffers
4b4104d87e28 ArmPkg/ArmDmaLib: implement DmaAllocateAlignedBuffer()
b56397ba9f67 BeagleBoardPkg: remove UncachedMemoryAllocationLib resolutions
c1d799b91509 Omap35xxPkg: remove bogus UncachedMemoryAllocationLib dependency

I will push the remaining patch that actually removes
UncachedMemoryAllocationLib once the dependencies are gone from
edk2-platforms.