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Re: Does grub crash UNDI service?

From: Yoshinori K. Okuji
Subject: Re: Does grub crash UNDI service?
Date: Fri, 19 Mar 2004 12:55:39 +0100
User-agent: KMail/1.5.3

On Friday 19 March 2004 08:28, Feng Shuo wrote:
> are suspicious: 1.    UNDI is resident in the high end of the lower
> memory and
> modifies the BIOS FBMS (at 40:13h) to avoid being crashed by the OS
> (i.e. GRUB) to load. After loaded, the Etherboot UNDI driver will
> release some unused UNDI data, allocate new space to install UNDI API
> and modify the FBMS to the new value. ---- I don't know where the
> GRUB always examines FBMS before it tries to write on the high end of
> the lower memory. If not, GRUB may have crashed the UNDI data before
> it call the driver again :(

It's likely. GRUB checks the lower memory only once when it starts up. 
Take a look at stage2/common.c.

> 2.    UNDI uses interrupt, so the UNDI driver set a
> 'trivial_irq_handler' after it is initialized. That seems to work
> fine at start, but I don't know whether it conflicts with grub I/O
> mechanic after grub get control. (The driver uses only one irq
> specified by UNDI ROM, but do not uninstall it until it is disabled)

Is it a real mode interrupt? If so, GRUB does not have any problem, but 
you might have to take care about that GRUB does not stay in protected 
mode too long.


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