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Fix harddisk detection for seriously broken BIOS

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svn path=/trunk/; revision=12197
This commit is contained in:
Gé van Geldorp 2004-12-18 19:53:30 +00:00
parent e8861acfb2
commit 2fa970d484
1 changed files with 20 additions and 0 deletions
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20
freeldr/freeldr/arch/i386/hardware.c
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@ -642,13 +642,33 @@ DetectBiosDisks(HKEY SystemKey,
U32 Size;
U32 i;
S32 Error;
BOOL Changed;
/* Count the number of visible drives */
DiskReportError(FALSE);
DiskCount = 0;
/* There are some really broken BIOSes out there. There are even BIOSes
* that happily report success when you ask them to read from non-existent
* harddisks. So, we set the buffer to known contents first, then try to
* read. If the BIOS reports success but the buffer contents haven't
* changed then we fail anyway */
memset((PVOID) DISKREADBUFFER, 0xcd, 512);
while (MachDiskReadLogicalSectors(0x80 + DiskCount, 0ULL, 1, (PVOID)DISKREADBUFFER))
{
Changed = FALSE;
for (i = 0; ! Changed && i < 512; i++)
{
Changed = ((PUCHAR)DISKREADBUFFER)[i] != 0xcd;
}
if (! Changed)
{
DbgPrint((DPRINT_HWDETECT, "BIOS reports success for disk %d but data didn't change\n",
(int)DiskCount));
break;
}
DiskCount++;
memset((PVOID) DISKREADBUFFER, 0xcd, 512);
}
DiskReportError(TRUE);
DbgPrint((DPRINT_HWDETECT, "BIOS reports %d harddisk%s\n",