Re: [PATCH 16/67] powerpc: rename dma_direct_ to dma_nommu_

[Julian Calaby]

Hi All,

On Wed, Jan 3, 2018 at 6:49 PM, Geert Uytterhoeven  wrote:
> Hi Michael,
>
> On Wed, Jan 3, 2018 at 7:24 AM, Michael Ellerman  wrote:
>> Geert Uytterhoeven  writes:
>>
>>> On Tue, Jan 2, 2018 at 10:45 AM, Michael Ellerman  
>>> wrote:
 Christoph Hellwig  writes:

> We want to use the dma_direct_ namespace for a generic implementation,
> so rename powerpc to the second best choice: dma_nommu_.

 I'm not a fan of "nommu". Some of the users of direct ops *are* using an
 IOMMU, they're just setting up a 1:1 mapping once at init time, rather
 than mapping dynamically.

 Though I don't have a good idea for a better name, maybe "1to1",
 "linear", "premapped" ?
>>>
>>> "identity"?
>>
>> I think that would be wrong, but thanks for trying to help :)
>>
>> The address on the device side is sometimes (often?) offset from the CPU
>> address. So eg. the device can DMA to RAM address 0x0 using address
>> 0x800.
>>
>> Identity would imply 0 == 0 etc.
>>
>> I think "bijective" is the correct term, but that's probably a bit
>> esoteric.
>
> OK, didn't know about the offset.
> Then "linear" is what we tend to use, right?

If this is indeed a linear mapping, can we just remove this and
replace it with the new "generic" mapping being introduced by this
patchset?

Thanks,

-- 
Julian Calaby

Email: julian.cal...@gmail.com
Profile: http://www.google.com/profiles/julian.calaby/

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Re: [PATCH] arch: drop duplicate exports of abort()

[Vineet Gupta]

On 01/02/2018 02:33 AM, Arnd Bergmann wrote:

We now have exports in both architecture code in in common code,
which causes a link failure when symbol versioning is eanbled, on
four architectures:

kernel/exit.o: In function `__crc_abort':
exit.c:(*ABS*+0xc0e2ec8b): multiple definition of `__crc_abort'

This removes the four architecture specific exports and only
leaves the export next to the __weak symbol.

Fixes: mmotm ("kernel/exit.c: export abort() to modules")
Signed-off-by: Arnd Bergmann 
---
Andrew, can you apply this to -mm on top of the other patch?
---
  arch/arc/kernel/traps.c   | 1 -
  arch/arm/kernel/traps.c   | 1 -
  arch/m32r/kernel/traps.c  | 1 -
  arch/unicore32/kernel/traps.c | 1 -
  4 files changed, 4 deletions(-)

diff --git a/arch/arc/kernel/traps.c b/arch/arc/kernel/traps.c
index 51a55b06cb2a..133a4dae41fe 100644
--- a/arch/arc/kernel/traps.c
+++ b/arch/arc/kernel/traps.c
@@ -169,4 +169,3 @@ void abort(void)
  {
__asm__ __volatile__("trap_s  5\n");
  }
-EXPORT_SYMBOL(abort);


FWIW, this hunk did not yet hit mainline. I've removed it from my patch in 
for-curr and re-pushed !


Thx,
-Vineet

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