Re: [PATCH 2/2]: acpica/nfit: Rename not-armed bit definition

[Linda Knippers]

On 8/26/2015 6:00 PM, Dan Williams wrote:
> On Wed, Aug 26, 2015 at 2:44 PM, Toshi Kani <toshi.kani@xxxxxx> wrote:
>> On Wed, 2015-08-26 at 14:30 -0700, Dan Williams wrote:
>>> On Wed, Aug 26, 2015 at 2:12 PM, Toshi Kani <toshi.kani@xxxxxx> wrote:
>>>> On Wed, 2015-08-26 at 10:16 -0700, Dan Williams wrote:
>>>>> On Wed, Aug 26, 2015 at 9:20 AM, Toshi Kani <toshi.kani@xxxxxx> wrote:
>>>>>> ACPI 6.0 NFIT Memory Device State Flags in Table 5-129 defines
>>>>>> bit 3 as follows.
>>>>>>
>>>>>>   Bit [3] set to 1 to indicate that the Memory Device is observed
>>>>>>   to be not armed prior to OSPM hand off. A Memory Device is
>>>>>>   considered armed if it is able to accept persistent writes.
>>>>>>
>>>>>> This bit is currently defined as ACPI_NFIT_MEM_ARMED, which can be
>>>>>> confusing as if the Memory Device is armed when this bit is set.
>>>>>>
>>>>>> Change the name to ACPI_NFIT_MEM_NOT_ARMED per the spec.
>>>>>>
>>>>>> Signed-off-by: Toshi Kani <toshi.kani@xxxxxx>
>>>>>> Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
>>>>>> Cc: Bob Moore <robert.moore@xxxxxxxxx>
>>>>>> Cc: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
>>>>>> ---
>>>>>>  drivers/acpi/nfit.c              |    6 +++---
>>>>>>  drivers/acpi/nfit.h              |    2 +-
>>>>>>  include/acpi/actbl1.h            |    2 +-
>>>>>
>>>>> This file "include/acpi/actbl1.h" is owned by the ACPICA project so
>>>>> any changes need to come through them.  But that said, I'm not sure we
>>>>> need friendly names at this level.
>>>>
>>>> I think the name is misleading, but I agree with the process and this
>>>> patch2
>>>> can be dropped.  It'd be nice if the ACPICA project can pick it up later
>>>> when they have a chance, though.
>>>>
>>>>> What I usually say about sysfs name changes to be more human friendly
>>>>> is "sysfs is not a UI", i.e. it's not necessarily meant to be user
>>>>> friendly.  As long as the names for the flags are distinct then
>>>>> wrapping descriptive / accurate names around them is the role of
>>>>> libndctl and userspace management software.
>>>>>
>>>>> Similar feedback for patch1 in the sense that I don't think we need to
>>>>> update the sysfs naming.  For example the API to retrieve the state of
>>>>> the "arm" flag in libndctl is ndctl_dimm_failed_arm().
>>>>
>>>> I agree that we do not want to change sysfs API for friendliness, and I
>>>> understand that libndctl already consumes the strings...  But I think
>>>> they
>>>> can be confusing for the long run, i.e. the flags is likely extended for
>>>> additional info, and more people may be looking at sysfs for the state.
>>>>  It'd be a lot harder to change them later.
>>>
>>> The starting premise though is that this will be nicer for scripts
>>> that want to avoid the library.  Properly handling the async device
>>> registration semantics of the libnvdimm-sysfs interface is hard to get
>>> right in a script.  I'm trying my best to discourage raw use of sysfs
>>> for this reason.  Small fixes to the names of flags seems to miss this
>>> wider point.
>>
>> Okay, I guess I will have to jump on the bandwagon and discourage people to
>> look at sysfs... ;-P
>>
> 
> That said, I'm not opposed to looking at something like Python-binding
> for libndctl to make scripting easier.

I don't see why we can't fix the names so they make sense now before there
is hardware in the market.  People doing testing and debugging look at stuff
in /sys and they write their own scripts too, not necessarily in python.

If they only make sense to someone using your library, I think we've missed the
mark.  Toshi is reacting to feedback we're getting from people are starting
to test this stuff.

-- ljk
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