amd64/111955: [install] Install CD boot panic due to missing BIOS smap on 5.5 through to 7.0-Current Snapshot 200704

[Eamon.Roque at arf.fak12.uni-muenchen.de]

The following reply was made to PR amd64/111955; it has been noted by GNATS.

From: Eamon.Roque at arf.fak12.uni-muenchen.de
To: "John Baldwin" <jhb at freebsd.org>
Cc: bug-followup at freebsd.org,
    Eamon.Roque at arf.fak12.uni-muenchen.de
Subject: Re: amd64/111955: [install] Install CD boot panic due to missing 
     BIOS smap on 5.5 through to 7.0-Current Snapshot 200704
Date: Mon, 18 Feb 2008 14:06:53 +0100 (CET)

 Would the amd64 kernel work the same way?
 
 I was able to boot the x86 cds, although I had to specify the physical
 memory size.
 
 The amd64 8.0-Current bootonly cd from Feb.7, 2008 panics as before
 because of the failed SMAP call.
 
 HTH
 
 Eamon Roque
 
 
 > So the SMAP problem is that in the one BIOS I looked at, the SMAP BIOS
 > call
 > only works from real mode.  Even if invoked from virtual 86 mode, the BIOS
 > call fails.  FreeBSD only calls the BIOS SMAP call from virtual 86 mode
 > both
 > in the loader and in the i386 kernel.  The fix is quite complicated and
 > involves rewriting the boot code to invoke BIOS calls from real mode
 > rather
 > than virtual 86 mode.
 >
 > --
 > John Baldwin
 >