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SubjectRe: Weird: 30 sec delay during early boot
On Tue, Jul 13, 2004 at 06:35:28PM -0400, Jeff Garzik wrote:
> Can you attach the patch, or switch mailers?
>
> The patch is word-wrapped and otherwise munged :(

That was sent with mutt-1.4.1-3 on a RHEL3 system...

Attached this time.
--
Matt Domsch
Sr. Software Engineer, Lead Engineer
Dell Linux Solutions linux.dell.com & www.dell.com/linux
Linux on Dell mailing lists @ http://lists.us.dell.com
===== arch/i386/boot/edd.S 1.2 vs edited =====
--- 1.2/arch/i386/boot/edd.S 2004-06-29 09:44:48 -05:00
+++ edited/arch/i386/boot/edd.S 2004-07-13 16:48:50 -05:00
@@ -12,13 +12,31 @@
#include <linux/edd.h>

#if defined(CONFIG_EDD) || defined(CONFIG_EDD_MODULE)
-# Read the first sector of each BIOS disk device and store the 4-byte signature
edd_mbr_sig_start:
+ xor %ebx, %ebx
+ xor %edx, %edx
movb $0, (EDD_MBR_SIG_NR_BUF) # zero value at EDD_MBR_SIG_NR_BUF
+ movw $EDD_MBR_SIG_BUF, %bx # store buffer ptr in bx
movb $0x80, %dl # from device 80
- movw $EDD_MBR_SIG_BUF, %bx # store buffer ptr in bx
+
edd_mbr_sig_read:
- movl $0xFFFFFFFF, %eax
+# Do int13 fn15 first, as BIOS should know if a disk is present or not.
+# This avoids long (>30s) delays waiting for the READ_SECTORS to a non-present disk.
+ xor %eax, %eax
+ xor %ecx, %ecx
+ movb $GETDISKTYPE, %ah # Function 15
+ pushw %dx # which stomps on dx
+ stc # work around buggy BIOSes
+ int $0x13 # make the call
+ sti # work around buggy BIOSes
+ popw %dx # so get back dx
+ jc edd_mbr_sig_done # no more BIOS devices
+ cmpb $HARDDRIVEPRESENT, %ah # is hard drive present?
+ jne edd_mbr_sig_done # no more BIOS devices
+
+# Read the first sector of each BIOS disk device and store the 4-byte signature
+ xor %ecx, %ecx
+ movl $0xFFFFFFFF, %eax
movl %eax, (%bx) # assume failure
pushw %bx
movb $READ_SECTORS, %ah
===== include/linux/edd.h 1.11 vs edited =====
--- 1.11/include/linux/edd.h 2004-06-29 09:44:48 -05:00
+++ edited/include/linux/edd.h 2004-07-13 16:05:14 -05:00
@@ -49,6 +49,9 @@
#define EDD_MBR_SIG_MAX 16 /* max number of signatures to store */
#define EDD_MBR_SIG_NR_BUF 0x1ea /* addr of number of MBR signtaures at EDD_MBR_SIG_BUF
in boot_params - treat this as 1 byte */
+#define GETDISKTYPE 0x15 /* int13 AH=0x15 is Get Disk Type command */
+#define HARDDRIVEPRESENT 0x03 /* int13 AH=15 return code in AH */
+
#ifndef __ASSEMBLY__

#define EDD_EXT_FIXED_DISK_ACCESS (1 << 0)
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