From: Michael Ellerman <mpe@ellerman.id.au>
To: Ira Weiny <ira.weiny@intel.com>, Vaibhav Jain <vaibhav@linux.ibm.com>
Cc: linuxppc-dev@lists.ozlabs.org, linux-nvdimm@lists.01.org,
linux-kernel@vger.kernel.org,
"Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>,
Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [RESEND PATCH v7 4/5] ndctl/papr_scm,uapi: Add support for PAPR nvdimm specific methods
Date: Thu, 21 May 2020 16:48:40 +1000 [thread overview]
Message-ID: <87367t941j.fsf@mpe.ellerman.id.au> (raw)
In-Reply-To: <20200520153209.GC3660833@iweiny-DESK2.sc.intel.com>
Ira Weiny <ira.weiny@intel.com> writes:
> On Wed, May 20, 2020 at 12:30:57AM +0530, Vaibhav Jain wrote:
>> Introduce support for Papr nvDimm Specific Methods (PDSM) in papr_scm
>> modules and add the command family to the white list of NVDIMM command
>> sets. Also advertise support for ND_CMD_CALL for the dimm
>> command mask and implement necessary scaffolding in the module to
>> handle ND_CMD_CALL ioctl and PDSM requests that we receive.
...
>> + *
>> + * Payload Version:
>> + *
>> + * A 'payload_version' field is present in PDSM header that indicates a specific
>> + * version of the structure present in PDSM Payload for a given PDSM command.
>> + * This provides backward compatibility in case the PDSM Payload structure
>> + * evolves and different structures are supported by 'papr_scm' and 'libndctl'.
>> + *
>> + * When sending a PDSM Payload to 'papr_scm', 'libndctl' should send the version
>> + * of the payload struct it supports via 'payload_version' field. The 'papr_scm'
>> + * module when servicing the PDSM envelope checks the 'payload_version' and then
>> + * uses 'payload struct version' == MIN('payload_version field',
>> + * 'max payload-struct-version supported by papr_scm') to service the PDSM.
>> + * After servicing the PDSM, 'papr_scm' put the negotiated version of payload
>> + * struct in returned 'payload_version' field.
>
> FWIW many people believe using a size rather than version is more sustainable.
> It is expected that new payload structures are larger (more features) than the
> previous payload structure.
>
> I can't find references at the moment through.
I think clone_args is a good modern example:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/include/uapi/linux/sched.h#n88
cheers
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next prev parent reply other threads:[~2020-05-21 6:49 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-19 19:00 [RESEND PATCH v7 0/5] powerpc/papr_scm: Add support for reporting nvdimm health Vaibhav Jain
2020-05-19 19:00 ` [RESEND PATCH v7 1/5] powerpc: Document details on H_SCM_HEALTH hcall Vaibhav Jain
2020-05-19 19:00 ` [RESEND PATCH v7 2/5] seq_buf: Export seq_buf_printf() to external modules Vaibhav Jain
2020-05-20 17:01 ` Christoph Hellwig
2020-05-19 19:00 ` [RESEND PATCH v7 3/5] powerpc/papr_scm: Fetch nvdimm health information from PHYP Vaibhav Jain
2020-05-20 14:54 ` Ira Weiny
2020-05-20 17:15 ` Vaibhav Jain
2020-05-21 14:31 ` Michael Ellerman
2020-05-21 16:59 ` Vaibhav Jain
2020-05-21 23:32 ` Ira Weiny
2020-05-19 19:00 ` [RESEND PATCH v7 4/5] ndctl/papr_scm,uapi: Add support for PAPR nvdimm specific methods Vaibhav Jain
2020-05-20 7:09 ` Aneesh Kumar K.V
2020-05-20 10:19 ` Vaibhav Jain
2020-05-20 15:32 ` Ira Weiny
2020-05-20 18:37 ` Vaibhav Jain
2020-05-21 6:48 ` Michael Ellerman [this message]
2020-05-22 7:38 ` [RESEND PATCH v7 4/5] ndctl/papr_scm, uapi: " Vaibhav Jain
2020-05-25 12:00 ` Vaibhav Jain
2020-05-26 12:14 ` Michael Ellerman
2020-05-19 19:00 ` [RESEND PATCH v7 5/5] powerpc/papr_scm: Implement support for PAPR_SCM_PDSM_HEALTH Vaibhav Jain
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