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From:   "Rafael J. Wysocki" <rafael@kernel.org>
Date:   Wed, 6 Dec 2023 17:30:47 +0100
Message-ID: <CAJZ5v0gGKuBNBvDj2fNMyCvKTrt2SWfusxyaf7W4jvvfL0nxUg@mail.gmail.com>
Subject: Re: [PATCH 1/1] ACPI: XSDT: struct acpi_table_xsdt must be packed
To:     Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
Cc:     Robert Moore <robert.moore@intel.com>,
        "Rafael J . Wysocki" <rafael@kernel.org>,
        Len Brown <lenb@kernel.org>, linux-acpi@vger.kernel.org,
        acpica-devel@lists.linux.dev, linux-kernel@vger.kernel.org
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On Sat, Nov 11, 2023 at 2:48 PM Heinrich Schuchardt
<heinrich.schuchardt@canonical.com> wrote:
>
> According to the ACPI 6.5 specification the component Entry starts at
> offset 36 in the XSDT table which is not a multiple of 8. Hence we must
> mark the structure as packed.

There is #pragma pack(1) at the beginning of actbl.h.  Is it not sufficient?

> We did not see an error due to the incorrect packing yet as in
> acpi_tb_parse_root_table() we use ACPI_ADD_PTR() to find the address of
> Entry.
>
> Signed-off-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
> ---
>  include/acpi/actbl.h | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/acpi/actbl.h b/include/acpi/actbl.h
> index 451f6276da49..1a37ac378765 100644
> --- a/include/acpi/actbl.h
> +++ b/include/acpi/actbl.h
> @@ -148,7 +148,7 @@ struct acpi_table_rsdt {
>  struct acpi_table_xsdt {
>         struct acpi_table_header header;        /* Common ACPI table header */
>         u64 table_offset_entry[1];      /* Array of pointers to ACPI tables */
> -};
> +} __packed;
>
>  #define ACPI_RSDT_ENTRY_SIZE        (sizeof (u32))
>  #define ACPI_XSDT_ENTRY_SIZE        (sizeof (u64))
> --
> 2.40.1
>