diff options
| author | yar <yar@FreeBSD.org> | 2004-08-28 08:32:23 +0000 |
|---|---|---|
| committer | yar <yar@FreeBSD.org> | 2004-08-28 08:32:23 +0000 |
| commit | 736cef795a523fe14c86bce1f473da19ff9b4988 (patch) | |
| tree | 2ebfadb60c7268d19d0271b676b7865b4a8ffd77 | |
| parent | 2032b765e70bf2638c33fea6437540f26aa24e2a (diff) | |
| download | FreeBSD-src-736cef795a523fe14c86bce1f473da19ff9b4988.zip FreeBSD-src-736cef795a523fe14c86bce1f473da19ff9b4988.tar.gz | |
Try packet mode of INT13 on a hard disk first if not prohibited by
the flag, fall back to the old INT13/AH=02 function if that fails.
This way of operation is less likely to fail with modern BIOSes and
large disks of strange geometries.
PR: i386/70241
Submitted by: Valentin Nechayev <netch <@> netch.kiev.ua> (inital version)
Discussed with: jhb (by Valentin Nechayev)
Tested on: bochs (with EDD turned on or off by patching the BIOS), PCs
| -rw-r--r-- | sys/boot/i386/boot2/boot1.S | 40 |
1 files changed, 21 insertions, 19 deletions
diff --git a/sys/boot/i386/boot2/boot1.S b/sys/boot/i386/boot2/boot1.S index 5b0f6f7..909cdf2 100644 --- a/sys/boot/i386/boot2/boot1.S +++ b/sys/boot/i386/boot2/boot1.S @@ -269,7 +269,25 @@ return: retw # To caller * %dl - byte - drive number * stack - 10 bytes - EDD Packet */ -read: push %dx # Save +read: testb $FL_PACKET,%cs:MEM_REL+flags-start # LBA support enabled? + jz read.1 # No, use CHS + cmpb $0x80,%dl # Hard drive? + jb read.1 # No, use CHS + mov $0x55aa,%bx # Magic + push %dx # Save + movb $0x41,%ah # BIOS: Check + int $0x13 # extensions present + pop %dx # Restore + jc read.1 # If error, use CHS + cmp $0xaa55,%bx # Magic? + jne read.1 # No, so use CHS + testb $0x1,%cl # Packet interface? + jz read.1 # No, so use CHS + mov %bp,%si # Disk packet + movb $0x42,%ah # BIOS: Extended + int $0x13 # read + retw # To caller +read.1: push %dx # Save movb $0x8,%ah # BIOS: Get drive int $0x13 # parameters movb %dh,%ch # Max head number @@ -292,7 +310,7 @@ read: push %dx # Save pop %dx # Restore cmpl $0x3ff,%eax # Cylinder number supportable? sti # Enable interrupts - ja read.7 # No, try EDD + ja ereturn # No, return an error xchgb %al,%ah # Set up cylinder rorb $0x2,%al # number orb %ch,%al # Merge @@ -328,24 +346,8 @@ read.4: movzbw %bl,%ax # Sectors read read.5: shlb %bl # buffer add %bl,0x5(%bp) # pointer, sub %al,0x2(%bp) # block count - ja read # If not done + ja read.1 # If not done read.6: retw # To caller -read.7: testb $FL_PACKET,%cs:MEM_REL+flags-start # LBA support enabled? - jz ereturn # No, so return an error - mov $0x55aa,%bx # Magic - push %dx # Save - movb $0x41,%ah # BIOS: Check - int $0x13 # extensions present - pop %dx # Restore - jc return # If error, return an error - cmp $0xaa55,%bx # Magic? - jne ereturn # No, so return an error - testb $0x1,%cl # Packet interface? - jz ereturn # No, so return an error - mov %bp,%si # Disk packet - movb $0x42,%ah # BIOS: Extended - int $0x13 # read - retw # To caller /* Messages */ |
