netdev - Re: [PATCH v7 24/28] cxl: add region flag for precluding a device memory to be used for dax

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Message-ID: <2dfb81cf-a606-3146-117b-5b5cf25ddbe9@amd.com>
Date: Wed, 11 Dec 2024 09:23:10 +0000
From: Alejandro Lucero Palau <alucerop@....com>
To: Edward Cree <ecree.xilinx@...il.com>, alejandro.lucero-palau@....com,
 linux-cxl@...r.kernel.org, netdev@...r.kernel.org, dan.j.williams@...el.com,
 martin.habets@...inx.com, edward.cree@....com, davem@...emloft.net,
 kuba@...nel.org, pabeni@...hat.com, edumazet@...gle.com, dave.jiang@...el.com
Subject: Re: [PATCH v7 24/28] cxl: add region flag for precluding a device
 memory to be used for dax


On 12/11/24 02:31, Edward Cree wrote:
> On 09/12/2024 18:54, alejandro.lucero-palau@....com wrote:
>> From: Alejandro Lucero <alucerop@....com>
>>
>> By definition a type2 cxl device will use the host managed memory for
>> specific functionality, therefore it should not be available to other
>> uses. However, a dax interface could be just good enough in some cases.
>>
>> Add a flag to a cxl region for specifically state to not create a dax
>> device. Allow a Type2 driver to set that flag at region creation time.
>>
>> Signed-off-by: Alejandro Lucero <alucerop@....com>
>> Reviewed-by: Zhi Wang <zhiw@...dia.com>
>> ---
>>   drivers/cxl/core/region.c | 10 +++++++++-
>>   drivers/cxl/cxl.h         |  3 +++
>>   drivers/cxl/cxlmem.h      |  3 ++-
>>   include/cxl/cxl.h         |  3 ++-
>>   4 files changed, 16 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/cxl/core/region.c b/drivers/cxl/core/region.c
>> index b014f2fab789..b39086356d74 100644
>> --- a/drivers/cxl/core/region.c
>> +++ b/drivers/cxl/core/region.c
>> @@ -3562,7 +3562,8 @@ __construct_new_region(struct cxl_root_decoder *cxlrd,
>>    * cxl_region driver.
>>    */
>>   struct cxl_region *cxl_create_region(struct cxl_root_decoder *cxlrd,
>> -				     struct cxl_endpoint_decoder *cxled)
>> +				     struct cxl_endpoint_decoder *cxled,
>> +				     bool no_dax)
> Won't this break bisectability?  sfc won't build as of this commit
>   because it tries to call cxl_create_region with the old signature.
> You could do the whole dance of having an interim API during the
>   conversion, but seems simpler just to reorder the patches so that
>   the no_dax parameter is added first before the caller is introduced.


Oh. That's true. I wonder why the robot did not catch this! I thought it 
was building things after each patch in a patchset.

I will change the order for properly using this in the sfc driver.

Thanks!