From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Dan Williams <dan.j.williams@intel.com>,
Linux ACPI <linux-acpi@vger.kernel.org>
Cc: Ross Zwisler <ross.zwisler@linux.intel.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Anaczkowski, Lukasz" <lukasz.anaczkowski@intel.com>,
"Box, David E" <david.e.box@intel.com>,
"Kogut, Jaroslaw" <Jaroslaw.Kogut@intel.com>,
"Koss, Marcin" <marcin.koss@intel.com>,
"Koziej, Artur" <artur.koziej@intel.com>,
"Lahtinen, Joonas" <joonas.lahtinen@intel.com>,
"Moore, Robert" <robert.moore@intel.com>,
"Nachimuthu, Murugasamy" <murugasamy.nachimuthu@intel.com>,
"Odzioba, Lukasz" <lukasz.odzioba@intel.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
"Schmauss, Erik" <erik.schmauss@intel.com>,
"Verma, Vishal L" <vishal.l.verma@intel.com>,
"Zheng, Lv" <lv.zheng@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
Balbir Singh <bsingharora@gmail.com>,
Brice Goglin <brice.goglin@gmail.com>,
Dave Hansen <dave.hansen@intel.com>,
Jerome Glisse <jglisse@redhat.com>,
John Hubbard <jhubbard@nvidia.com>, Len Brown <lenb@kernel.org>,
Tim Chen <tim.c.chen@linux.intel.com>,
Linux MM <linux-mm@kvack.org>,
"linux-nvdimm@lists.01.org" <linux-nvdimm@lists.01.org>
Subject: Re: [PATCH v3 1/3] acpi: HMAT support in acpi_parse_entries_array()
Date: Sat, 16 Dec 2017 02:53:07 +0100 [thread overview]
Message-ID: <1658696.rIK19Js0WO@aspire.rjw.lan> (raw)
In-Reply-To: <CAPcyv4gnZ3NJsEUugjBrsBHcs9-yqxkvs_G4V1HHGWF2JDi13g@mail.gmail.com>
On Friday, December 15, 2017 2:10:17 AM CET Dan Williams wrote:
> On Wed, Dec 13, 2017 at 6:10 PM, Ross Zwisler
> <ross.zwisler@linux.intel.com> wrote:
> > The current implementation of acpi_parse_entries_array() assumes that each
> > subtable has a standard ACPI subtable entry of type struct
> > acpi_subtable_header. This standard subtable header has a one byte length
> > followed by a one byte type.
> >
> > The HMAT subtables have to allow for a longer length so they have subtable
> > headers of type struct acpi_hmat_structure which has a 2 byte type and a 4
> > byte length.
>
> Hmm, NFIT has a 2 byte type and a 2 byte length, so its one more
> permutation. I happened to reinvent sub-table parsing in the NFIT
> driver, but it might be nice in the future to refactor that to use the
> common parsing.
>
> >
> > Enhance the subtable parsing in acpi_parse_entries_array() so that it can
> > handle these new HMAT subtables.
> >
> > Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
> > ---
> > drivers/acpi/tables.c | 52 ++++++++++++++++++++++++++++++++++++++++-----------
> > 1 file changed, 41 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/acpi/tables.c b/drivers/acpi/tables.c
> > index 80ce2a7d224b..f777b94c234a 100644
> > --- a/drivers/acpi/tables.c
> > +++ b/drivers/acpi/tables.c
> > @@ -218,6 +218,33 @@ void acpi_table_print_madt_entry(struct acpi_subtable_header *header)
> > }
> > }
> >
> > +static unsigned long __init
> > +acpi_get_entry_type(char *id, void *entry)
> > +{
> > + if (strncmp(id, ACPI_SIG_HMAT, 4) == 0)
> > + return ((struct acpi_hmat_structure *)entry)->type;
> > + else
> > + return ((struct acpi_subtable_header *)entry)->type;
> > +}
>
> It seems inefficient to make all checks keep asking "is HMAT?".
Well, ideally, the signature should be checked once. I guess that can be
arranged for here.
> Especially if we want to extend this to other table types should we
> instead setup and pass a pair of function pointers to parse the
> sub-table format?
Function pointers may be too much even. :-)
Thanks,
Rafael
next prev parent reply other threads:[~2017-12-16 1:53 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-14 2:10 [PATCH v3 0/3] create sysfs representation of ACPI HMAT Ross Zwisler
2017-12-14 2:10 ` [PATCH v3 1/3] acpi: HMAT support in acpi_parse_entries_array() Ross Zwisler
2017-12-15 0:49 ` Rafael J. Wysocki
2017-12-15 1:10 ` Dan Williams
2017-12-16 1:53 ` Rafael J. Wysocki [this message]
2017-12-16 1:57 ` Dan Williams
2017-12-16 2:15 ` Rafael J. Wysocki
2017-12-14 2:10 ` [PATCH v3 2/3] hmat: add heterogeneous memory sysfs support Ross Zwisler
2017-12-15 0:52 ` Rafael J. Wysocki
2017-12-15 20:53 ` Ross Zwisler
2017-12-14 2:10 ` [PATCH v3 3/3] hmat: add performance attributes Ross Zwisler
2017-12-14 13:00 ` [PATCH v3 0/3] create sysfs representation of ACPI HMAT Michal Hocko
2017-12-18 20:35 ` Ross Zwisler
2017-12-20 16:41 ` Ross Zwisler
2017-12-21 13:18 ` Michal Hocko
2017-12-20 18:19 ` Matthew Wilcox
2017-12-20 20:22 ` Dave Hansen
2017-12-20 21:16 ` Matthew Wilcox
2017-12-20 21:24 ` Ross Zwisler
2017-12-20 22:29 ` Dan Williams
2017-12-20 22:41 ` Ross Zwisler
2017-12-21 20:31 ` Brice Goglin
2017-12-22 22:53 ` Dan Williams
2017-12-22 23:22 ` Ross Zwisler
2017-12-22 23:57 ` Dan Williams
2017-12-23 1:14 ` Rafael J. Wysocki
2017-12-27 9:10 ` Brice Goglin
2017-12-30 6:58 ` Matthew Wilcox
2017-12-30 9:19 ` Brice Goglin
2017-12-20 21:13 ` Ross Zwisler
2017-12-21 1:41 ` Elliott, Robert (Persistent Memory)
2017-12-22 21:46 ` Ross Zwisler
2017-12-21 12:50 ` Michael Ellerman
2017-12-22 3:09 ` Anshuman Khandual
2017-12-22 10:31 ` Kogut, Jaroslaw
2017-12-22 14:37 ` Anshuman Khandual
2017-12-22 17:13 ` Dave Hansen
2017-12-23 5:14 ` Anshuman Khandual
2017-12-22 22:13 ` Ross Zwisler
2017-12-23 6:56 ` Anshuman Khandual
2017-12-22 22:31 ` Ross Zwisler
2017-12-25 2:05 ` Liubo(OS Lab)
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