Re: grub 0.90 prevents Standby in Windows

[erich]

Thierry Laronde <address@hidden> wrote:

> > As the only thing I've changed was the Installation of Mandrake 
> > and grub I cleared the mbr from a Win bootdisk and started the system.
> > After that the standby-option was present again and worked well.
> > I thought that something went wrong with the grub-installation and so I 
> > bootet my Linux from a bootdisk and reinstalled grub.
...

> Just a question, since some of us (I for one) don't have Windows, what
> is the standby-mode in Windows. Something related to APM or ACPI I
> guess?

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.

The current version of GRUB appears to use an APM checking/initialization
routing similar to that of the Linux kernel's setup code.

I know for a fact that the Linux kernel's APM setup code is busted in
the sense that it leaves the APM in a "connected" state, and the
kernel command-line option to disable APM doesn't fix this, only
removing it from the kernel compile entirely does.  This is incorrect
behavior in that it will confuse some OSes (such as Windows
in this case I would guess), and on some motherboards when you enable
APIC and IO-APIC operation, it will cause random crashes for no
apparent reason.  I debugged a few cases of exactly this problem at
one point.

Under Linux, the only "workaround" is to disable APIC and IO-APIC
operation on such machines, even if no other code ever refers to APM.

This is not an option for some other OSes, and that plus the fact that
most OSes expect that the bootloader has not mucked with the APM state
means GRUB should at the very least *always* disconnect afterward.

The bootloader shouldn't muck with the BIOS in an irreversible manner
unless you ask it to.

I'm going to test this out tonight.

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