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From: "Rafael J. Wysocki" <rafael@kernel.org>
To: "Moore, Robert" <robert.moore@intel.com>
Cc: Hans de Goede <hdegoede@redhat.com>,
	"Zheng, Lv" <lv.zheng@intel.com>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Len Brown <lenb@kernel.org>,
	"linux-acpi@vger.kernel.org" <linux-acpi@vger.kernel.org>,
	"devel@acpica.org" <devel@acpica.org>,
	"Box, David E" <david.e.box@intel.com>
Subject: Re: [PATCH] ACPICA: Detect duplicate SSDT tables
Date: Wed, 1 Mar 2017 22:56:46 +0100	[thread overview]
Message-ID: <CAJZ5v0i70OWDZXb7CObRykiEpgQ_=1QWA2ZQM9YYQipVLPbaxg@mail.gmail.com> (raw)
In-Reply-To: <94F2FBAB4432B54E8AACC7DFDE6C92E37E56876F@ORSMSX110.amr.corp.intel.com>

On Wed, Mar 1, 2017 at 9:38 PM, Moore, Robert <robert.moore@intel.com> wrote:
> Sorry if I've missed any of this conversation, but I have a couple of thoughts:
>
> 1) It might be sufficient to just compare the incoming table header (36 bytes). The header contains both the table length and the checksum -- as well as the OEM ID and OEM version. I take it that the XSDT pointers to the duplicate tables are different.
>
> 2) As far as comparing every incoming SSDT byte-for-byte against all previously loaded SSDTs, I have to think "what about the boot time?". Especially since SSDTs are increasing in both size and number (See example from a real machine below).
>
>
> ACPI: RSDP 0x0000000000492954 000024 (v02 Intel )
> ACPI: XSDT 0x000000000068C938 0000B4 (v00 Intel  AcpiExec 00001001 INTL 20170224)
> ACPI: FACP 0x0000000000492978 000114 (v05 Intel  AcpiExec 00001001 INTL 20170224)
> ACPI: DSDT 0x0000000000690048 022FD6 (v02 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: FACS 0x0000000000492AB0 000040
> ACPI: SSDT 0x00000000006B3028 0004B7 (v02 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: SSDT 0x000000000068D940 000B49 (v02 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: SSDT 0x00000000006B34E8 0004A3 (v02 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: SSDT 0x00000000006B3998 000E58 (v02 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: SSDT 0x00000000006B47F8 00037F (v02 PmRef  Cpu0Cst  00003001 INTL 20121220)
> ACPI: SSDT 0x000000000068E498 000660 (v02 PmRef  Cpu0Ist  00003000 INTL 20121220)
> ACPI: SSDT 0x00000000006B4B80 0005AA (v02 PmRef  ApIst    00003000 INTL 20121220)
> ACPI: SSDT 0x000000000068EB00 000119 (v02 PmRef  ApCst    00003000 INTL 20121220)
> ACPI: SSDT 0x000000000068EC28 00004B (v02 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: SSDT 0x00000000006B5138 0052EE (v02 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: SSDT 0x00000000006BA430 002C4A (v02 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: SSDT 0x00000000006BD088 0004C8 (v02 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: SSDT 0x000000000068EC80 0002D4 (v01 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: SSDT 0x00000000006BD558 002BAE (v02 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: SSDT 0x00000000006C0110 00019A (v02 LENOVO CB-01    00000001 ACPI 00040000)
> ACPI: SSDT 0x00000000006C02B8 0006DC (v02 LENOVO CB-01    00000001 ACPI 00040000)
>

Right.

Whatever allows us to make a "we've loaded this table already, skip
it" decision without comparing byte-for-byte, please.

Thanks,
Rafael

  reply	other threads:[~2017-03-02  3:58 UTC|newest]

Thread overview: 30+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-27  9:34 [PATCH] ACPICA: Detect duplicate SSDT tables Hans de Goede
2017-02-28  5:19 ` Zheng, Lv
2017-02-28 14:31   ` Hans de Goede
2017-02-28 15:46     ` Moore, Robert
2017-02-28 23:44       ` Hans de Goede
2017-03-01  0:11         ` Moore, Robert
2017-03-01  3:21     ` Zheng, Lv
2017-03-01  9:19       ` Hans de Goede
2017-03-01 20:38         ` Moore, Robert
2017-03-01 21:56           ` Rafael J. Wysocki [this message]
2017-03-02  1:59         ` Zheng, Lv
2017-03-02 15:24           ` Hans de Goede
2017-03-03  2:50             ` Zheng, Lv
2017-03-03 13:52               ` Hans de Goede
2017-03-13  6:01                 ` Zheng, Lv
2017-05-16  7:13 ` [RFC PATCH v2 0/5] ACPICA: Tables: Add deferred verification support Lv Zheng
2017-05-16  7:13   ` [RFC PATCH v2 1/5] ACPICA: Tables: Cleanup table handler invokers Lv Zheng
2017-05-16  7:13   ` [RFC PATCH v2 2/5] ACPICA: Tables: Do not validate signature for dynamic table load Lv Zheng
2017-05-16  7:13   ` [RFC PATCH v2 3/5] ACPICA: Tables: Change table duplication check to be related to acpi_gbl_verify_table_checksum Lv Zheng
2017-05-16  7:13   ` [RFC PATCH v2 4/5] ACPICA: Tables: Combine checksum/duplication verification together Lv Zheng
2017-05-16  7:13   ` [RFC PATCH v2 5/5] ACPICA: Tables: Add deferred table verification support Lv Zheng
2017-05-18 14:01   ` [RFC PATCH v2 0/5] ACPICA: Tables: Add deferred " Hans de Goede
2017-05-19  7:59     ` Zheng, Lv
2017-05-19  9:49       ` Hans de Goede
2017-05-18  9:57 ` [RFC PATCH v3 " Lv Zheng
2017-05-18  9:57   ` [RFC PATCH v3 1/5] ACPICA: Tables: Cleanup table handler invokers Lv Zheng
2017-05-18  9:57   ` [RFC PATCH v3 2/5] ACPICA: Tables: Do not validate signature for dynamic table load Lv Zheng
2017-05-18  9:57   ` [RFC PATCH v3 3/5] ACPICA: Tables: Change table duplication check to be related to acpi_gbl_verify_table_checksum Lv Zheng
2017-05-18  9:57   ` [RFC PATCH v3 4/5] ACPICA: Tables: Combine checksum/duplication verification together Lv Zheng
2017-05-18  9:57   ` [RFC PATCH v3 5/5] ACPICA: Tables: Add deferred table verification support Lv Zheng

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