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Date: Fri, 8 Feb 2008 22:23:17 +0100
From: Pavel Machek <pavel@ucw.cz>
To: Alan Stern <stern@rowland.harvard.edu>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>,
       Linux-pm mailing list <linux-pm@lists.osdl.org>,
       kernel list <linux-kernel@vger.kernel.org>,
       "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [linux-pm] Re: [rft] s2ram wakeup moves to .c, could fix few
	machines
Message-ID: <20080208212317.GD12923@elf.ucw.cz>
References: <20080208210004.GA12923@elf.ucw.cz> <Pine.LNX.4.44L0.0802081617280.5958-100000@iolanthe.rowland.org>
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Hi!

> > > > segments:offsets rear its ugly head here. I need %ds to point to my
> > > > data, and the way to do it is copy it from %cs; that needs start to be
> > > > at 0.
> > > 
> > > Hm, why exactly is that necessay?
> > 
> > It is not _neccessary_. Try to come up with another method that gets
> > relocations right. I could not :-(.
> > 
> > (Actually, putting table at the offset 0 and short jump at beggining
> > of the table would probably do the trick. But that still keeps code at
> > offset 0 :-).
> 
> Pavel, can you explain in greater detail exactly what you need?

I do not think I need anything. I'm just explaining why data need to
go at nonzero offset. Nothing to see here, move on ;-).

> It sounds like you are running in real mode with code stored at some 
> (unknown?) location in memory.  The BIOS calls this code with IP=0 and 
> CS=<something>, which apparently doesn't fit your requirements.

> So just what are your requirements?  The only possibilities I can think 
> of are:
> 
> 	Code stored at a particular location in memory;
> 
> 	CS, IP, etc. initialized to some particular values.
> 
> What am I missing?

See arch/x86/kernel/acpi/realmode/wakeup.S (the version that was sent
to the list). No problem there, but table stored at nonzero
offset. Short jump at the beggining of table would fix it (ugly).

									Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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