[PATCH]: Correctly locate RSDP in EBDA

[Udo A. Steinberg]

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ACPI spec. states that the location of the RSDP structure is found by searc=
hing
* The first 1 KB of the Extended BIOS Data Area (EBDA).
* The BIOS read-only memory space between 0E0000h and 0FFFFFh

The EBDA scan looks wrong. The patch below against 2.6.12 should correct th=
is.

-Udo.

---

Calculate correct EBDA address for ACPI RSDP scan. The word at BIOS Data Ar=
ea
40:0E is the segment address of the EBDA.

Signed-off-by: Udo A. Steinberg <us15@xxxxxxxxxxxxxxxxxxxx>

--- linux-2.6.12/arch/i386/kernel/acpi/boot.c.old       2005-07-20 17:28:32=
.000000000 +0200
+++ linux-2.6.12/arch/i386/kernel/acpi/boot.c   2005-07-20 17:31:15.0000000=
00 +0200
@@ -648,7 +648,7 @@
         * Scan memory looking for the RSDP signature. First search EBDA (l=
ow
         * memory) paragraphs and then search upper memory (E0000-FFFFF).
         */
-       rsdp_phys =3D acpi_scan_rsdp (0, 0x400);
+       rsdp_phys =3D acpi_scan_rsdp (*(u16*) 0x40E << 4, 0x400);
        if (!rsdp_phys)
                rsdp_phys =3D acpi_scan_rsdp (0xE0000, 0x20000);
=20

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