Subject: Linux vs. 486/33
Date: Sat, 16 Nov 91 01:03:49 -0700
From: John T Kohl <jtkohl@Athena.MIT.EDU>
To: linux-activists@joker.cs.hut.fi

I just got a new 486/33 today, and linux only seems to want to boot if
the "turbo" switch is turned off.  If I turn it once I'm running ,it
seems to cause no problems.

I'm booting off a 1.44MB 3.5" floppy.

John

Subject: Re: Linux vs. 486/33
Date: Sat, 16 Nov 91 20:58:55 -0500
From: tytso@ATHENA.MIT.EDU (Theodore Ts'o)
To: John T Kohl <jtkohl@Athena.MIT.EDU>
Cc: linux-activists@joker.cs.hut.fi
In-Reply-To: John T Kohl's message of Sat, 16 Nov 91 01:03:49 -0700,
Reply-To: tytso@athena.mit.edu

   Date: Sat, 16 Nov 91 01:03:49 -0700
   From: John T Kohl <jtkohl@Athena.MIT.EDU>

   I just got a new 486/33 today, and linux only seems to want to boot if
   the "turbo" switch is turned off.  If I turn it once I'm running ,it
   seems to cause no problems.

Interesting.... I have no problems running at 40Mhz on my 386.  How does
it die?

							- Ted

Subject: more on 486/33 weirdness
Date: Sat, 16 Nov 91 23:11:47 PST
To: linux-activists@joker.cs.hut.fi
From: John T Kohl <jtkohl@cs.berkeley.edu>
Reply-To: jtkohl@cs.berkeley.edu

Here are more details on my problems with booting in turbo mode:

system config:
	486DX/33, 256K cache, 8MB main memory
	American Megatrends, Inc. BIOS
	real-time clock
	1 3.5" floppy (A:), 1 5.25" floppy (B:)
	1 200MB IDE drive (connor)
		C:, /dev/hd2, /dev/hd3, D: partitions (in that order)
	SVGA: (Orchid ProDesigner IIs/1MB)

I boot off the 3.5" floppy, with root partition on /dev/hd2 and/or /dev/hd3.

sample errors when in "turbo" (33MHz) mode:

<startup stuff>
Partition table Ok.
general protection: 0000
EIP 0008:0000CBB3
EFLAGS 0010206
ESP 0300:0001D210
fs: 0010
base 04000000, limit 000A0000
Pid: 1, process number 1
f3 a5 50 e8 7d fb ff ff 83 c4

... or

general protection: 67b4
EIP 10008:00000004
EFLAGS 00010206
ESP 0020:000067B6
fs: 0010
base 04000000, limit 000A0000
Pid: 1, process number 1
07 20 00 00 27 30 00 00 07 40


sometimes I get two "general protection" errors (same process, usually).

When I toggle the turbo on & off while running, I don't observe any
change in running times of programs (but I can discern differences under
MS-DOS 5.0), even when I run programs which try to time themselves.

Any suggestions?

Subject: Re: 486 problem
Date: Mon, 6 Jan 92 11:52:59 PST
To: nicholas@cs.uwa.oz.au (Nicholas Yue)
Cc: linux-activists@joker.cs.hut.fi
In-Reply-To: [128]
From: John T Kohl <jtkohl@cs.berkeley.edu>
Reply-To: jtkohl@cs.berkeley.edu

I finally found and corrected the problem I had with booting a 486/33 at
full speed.

The problem was the BIOS "Fast A20 Gate Option".  For UNIXes, this
should be DISABLED; for Mess-Dos, it seems to make no difference.
[A droid at the computer store said it has something to do with DMA]

John

Subject: Re: 486 problem
Date: Tue, 7 Jan 92 11:25:50 PST
To: linux-activists@joker.cs.hut.fi
Cc: nicholas@cs.uwa.oz.au (Nicholas Yue)
In-Reply-To: [306]
From: John T Kohl <jtkohl@cs.berkeley.edu>
Reply-To: jtkohl@cs.berkeley.edu

Yesterday I said:

> The problem was the BIOS "Fast A20 Gate Option".

Actually, that wasn't it.  At the same time, I upgraded to 4M simms
rather than 1M simms, and the problem went away.  Oh well...?

John