Re: [PATCH 1/6] RMDA/sw: don't allow drivers using dma_virt_ops on highmem configs

[Christoph Hellwig <hch@lst.de>]

On Thu, Nov 05, 2020 at 12:15:46PM +0000, Robin Murphy wrote:
> On 2020-11-05 07:42, Christoph Hellwig wrote:
>> dma_virt_ops requires that all pages have a kernel virtual address.
>> Introduce a INFINIBAND_VIRT_DMA Kconfig symbol that depends on !HIGHMEM
>> and a large enough dma_addr_t, and make all three driver depend on the
>> new symbol.
>>
>> Signed-off-by: Christoph Hellwig <hch@lst.de>
>> ---
>>   drivers/infiniband/Kconfig           | 6 ++++++
>>   drivers/infiniband/sw/rdmavt/Kconfig | 3 ++-
>>   drivers/infiniband/sw/rxe/Kconfig    | 2 +-
>>   drivers/infiniband/sw/siw/Kconfig    | 1 +
>>   4 files changed, 10 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/infiniband/Kconfig b/drivers/infiniband/Kconfig
>> index 32a51432ec4f73..81acaf5fb5be67 100644
>> --- a/drivers/infiniband/Kconfig
>> +++ b/drivers/infiniband/Kconfig
>> @@ -73,6 +73,12 @@ config INFINIBAND_ADDR_TRANS_CONFIGFS
>>   	  This allows the user to config the default GID type that the CM
>>   	  uses for each device, when initiaing new connections.
>>   +config INFINIBAND_VIRT_DMA
>> +	bool
>> +	default y
>> +	depends on !HIGHMEM
>> +	depends on !64BIT || ARCH_DMA_ADDR_T_64BIT
>
> Isn't that effectively always true now since 4965a68780c5? I had a quick 
> try of manually overriding CONFIG_ARCH_DMA_ADDR_T_64BIT in my .config, and 
> the build just forces it back to "=y".

True.  The guy who did the commit should have really told me about it :)