Re: ACPI WARNING: at drivers/acpi/tables/tbfadt.c:348 acpi_tb_create_local_fadt+0x147/0x2f4()

From: Andi Kleen
Date: Thu Jul 17 2008 - 05:06:32 EST

Jan Beulich wrote:

So it's a firmware bug in the system you saw this on. The specification
is clear about the width being at least 16 bits, and the warning was added
to indicate the problem you now got: Dividing 8 by 16 yields zero for
pm1_register_length, which results in acpi_gbl_xpm1a_enable aliasing
the address of the respective status register. That won't work, hence
the warning.

When there are systems around where this register is 8 bits then we have to handle it. Real systems beat the specification.

The question is just if the hardware is really 8 bits or if the table
is not just wrong. What does lspci say?

Also, I noticed that the patch changed the definition of
acpi_tb_init_generic_address to name the parameter byte_width instead
of bit_width. The declaration at the top of the file and the
documentation still refer to it as bit_width.

I also added printk()s to the first call to
acpi_tb_init_generic_address ~ line 326 and the lengths passed to the
function at that point are:
[ 0.000000] fadt_info_table[i].length=88
[ 0.000000] fadt_info_table[i].length=89
[ 0.000000] fadt_info_table[i].length=93

Hmm, indeed, I didn't notice the (pointless) earlier declaration, I realize
I failed to update the function description. Bob, could you fix this in
ACPICA without the need for me to send a patch against it (assuming
the base patch went into ACPICA)?

No it went directly.


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