Re: [PATCH] exec: fetch the alignment of Linux devdax pmem character device nodes

[Joao Martins]

On 4/8/20 2:16 AM, Liu, Jingqi wrote:
> On 4/7/2020 11:51 PM, Joao Martins wrote:
>> On 4/7/20 3:31 PM, Paolo Bonzini wrote:
>>> On 07/04/20 12:59, Joao Martins wrote:
>>>> Perhaps, you meant instead:
>>>>
>>>>    /sys/dev/char/%d:%d/align
>>>>
>>>>   ?
>>>>
> Hi Joao,
> 
> In my machine with real NVDIMM, the devdax device is as follows:
> 
> $ ll /dev/dax0.0
> crw------- 1 root root 250, 6 3月  25 15:16 /dev/dax0.0
> 
> $ ls /sys/dev/char/250\:6/align
> ls: cannot access '/sys/dev/char/250:6/align': No such file or directory
> 
> $ ls /sys/dev/char/250\:6/device/align
> 
> /sys/dev/char/250:6/device/align
> 
> So:
> The file of "/sys/dev/char/%d:%d/align" does not exist.
> It should be "/sys/dev/char/%d:%d/device/align".
> 
The 'align' (without the ../) was my mistake as I was testing with other wip
patches.

Albeit, still retain my comment to 'device/align' as it is relying on an
deprecated path, so perhaps we should look other alternatives.

I had the deprecated dax class disabled (DEV_DAX_PMEM_COMPAT=n), and 'device'
does not exist on that cases.



> Anyone has a real NVDIMM can help double check. Thanks.
> 
> Hi Dan,
> 
> You may have a real NVDIMM, in what directory is the 'align' file ?
> 
> Thanks,
> 
> Jingqi
> 
>>> So it works with that change?
>> Yeah.
>>
>>      Joao