[PATCH] Re: grub 0.90 prevents Standby in Windows

[erich]

address@hidden wrote:

...
> I have the same problem, and think I know what it is.
> 
> I think it's the presence of APM checking code in GRUB itself (at least
> in 0.90 and later) that's the issue.  I've only read the CVS sources
> in any detail, but it probably applies.
...
> I'm going to test this out tonight.


OK, it turns out that this was indeed the problem.

I have a patch here which unconditionally performs an APM "disconnect"
at the end of the probing process, and that resolved it on both of my
machines I tested it on.

This file is somewhat old (last change about a year ago), so my guess
is that it's probably identical in the 0.90 version, and therefore
RedHat's version as well.

Which makes me wonder, should we fix the other changed bits in booting
then try to release a new GRUB version, say 0.91?


-------------------------(start patch here)-----------------------
--- grub.orig/stage2/apm.S      Tue Oct 24 23:16:16 2000
+++ grub/stage2/apm.S           Fri Oct 26 11:45:04 2001
@@ -91,12 +91,12 @@
   xorw   %cx, %cx
   int     $0x15
   /* error -> should not happen, tidy up */
-  jc apm_disconnect
+  jc done_apm_bios
 
        /* check for "PM" signature */
        cmpw     $0x504d, %bx
        /* no signature -> should not happen, tidy up */
-       jne   apm_disconnect
+       jne   done_apm_bios
 
        /* record the APM BIOS version */
        movw      %ax, ABS(EXT_C(apm_bios_info))
@@ -104,19 +104,17 @@
   movw    %cx, ABS(EXT_C(apm_bios_info)) + 12
   jmp     done_apm_bios
 
-apm_disconnect:
-       /* Disconnect */
-       movw          $0x5304, %ax
-       xorw          %bx, %bx
-       /* ignore return code */
-       int     $0x15
-       jmp     done_apm_bios
-
 no_32_apm_bios:
        /* remove 32 bit support bit */
        andw     $0xfffd, ABS(EXT_C(apm_bios_info)) + 12
 
 done_apm_bios:
+       /* Some paranoia here: Always Disconnect from APM */
+       movw    $0x5304, %ax
+       xorw    %bx, %bx
+       /* ignore return code */
+       int     $0x15
+
        DATA32  call    EXT_C(real_to_prot)
        .code32
 
-------------------------(end patch here)-----------------------


--
    Erich Stefan Boleyn     <address@hidden>     http://www.uruk.org/
"Reality is truly stranger than fiction; Probably why fiction is so popular"