Re: ACPI: RSDP - ERROR: Invalid checksum

[Klaus Muth <muth-5lHx5lHeYlQ@public.gmane.org>]

Am Mittwoch, 8. Juni 2005 15:29 schrieb Klaus Muth:
> Hi!
>
> Ok, I do the Ingrid.
AAARGH. Another Ingrid. Seems, that the acpi_find_rsdp() is rather optimistic 
about finding the RSDP [arch/i386/kernel/acpi/boot.c, acpi_scan_rsdp]:
 /*
  * Scan all 16-byte boundaries of the physical memory region for the
  * RSDP signature.
  */
 for (offset = 0; offset < length; offset += 16) {
  if (strncmp((char *) (start + offset), "RSD PTR ", sig_len))
   continue;
  return (start + offset);
 }

It seems to happen, that the IBM BIOS contains just the string "RSD PTR " 
exactly at a 16-Byte-Boundary before the real RSDP block, so the wrnog 
address is returned and acpi_table_init() in drivers/acpi/tables.c fails to 
checksum this block of course.

The patched up RedHat Kernel uses 
static struct acpi_table_rsdp * __init
acpi_find_root_pointer(void)
{
 struct acpi_table_rsdp * rsdp;

 /*
  * Physical address is given
  */
 /*
  * Region 1) Search EBDA (low memory) paragraphs
  */
 rsdp = acpi_tb_scan_memory_for_rsdp(__va(LO_RSDP_WINDOW_BASE),
      LO_RSDP_WINDOW_SIZE);

 if (rsdp)
  return rsdp;

 /*
  * Region 2) Search upper memory: 16-byte boundaries in E0000h-F0000h
  */
 rsdp = acpi_tb_scan_memory_for_rsdp(__va(HI_RSDP_WINDOW_BASE),
            HI_RSDP_WINDOW_SIZE);

 
          
 if (rsdp)
  return rsdp;

 printk(KERN_ERR "ACPI: System description tables not found\n");
 return NULL;
}

to find the RSDP and seems to find it in Region 2. GRRRR.

Is there any patch to do the same with a vanilla 2.6 Kernel?
-- 
Klaus Muth
HAGOS eG                      Industriestr. 62      fon: (+49) 711 78805-86
EDV-Programmierung            70565  Stuttgart      fax: (+49) 711 78805-35
http://www.hagos.de               Germany              mailto:muth-5lHx5lHeYlQ@public.gmane.org


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