Hi,
On Wed, 2007-09-05 at 04:29 +0200, Stefan Reinauer wrote:
> * Alex Beregszaszi <[EMAIL PROTECTED]> [070904 13:17]:
> > Hi,
> >
> > the attached patch adds code to checksum the pci extension rom and stop
> > if the stored and calculated checksum differ.
>
> Is this checksum reliably correct? I am hesitating to add new
> restrictions that might break otherwise working cards.
You are right, attached is a correct method. There is no fixed checksum
byte, instead the whole should sum to zero.
--
Alex
Signed-off-by: Alex Beregszaszi <[EMAIL PROTECTED]>
Index: device/pci_rom.c
===================================================================
--- device/pci_rom.c (revision 494)
+++ device/pci_rom.c (working copy)
@@ -33,6 +33,8 @@
unsigned long rom_address;
struct rom_header *rom_header;
struct pci_data *rom_data;
+ unsigned int i;
+ unsigned char sum = 0, *rom_bytes;
if (dev->on_mainboard) {
/* In case some device PCI_ROM_ADDRESS can not be set
@@ -67,7 +69,17 @@
le32_to_cpu(rom_header->signature));
return NULL;
}
+
+ /* checksum */
+ rom_bytes = (unsigned char *)rom_address;
+ for (i = 0; i < rom_header->size * 512; i++)
+ sum += *(rom_bytes + i);
+ if (sum != 0) {
+ printk(BIOS_ERR, "Incorrent Expansion ROM checksum (%02x != 0)\n", sum);
+ return NULL;
+ }
+
rom_data = (struct pci_data *)((unsigned char *)rom_header +
le32_to_cpu(rom_header->data));
--
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