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* Linux Post codes during runtime, possibly OT
@ 2001-01-25 21:46 Ian S. Nelson
  2001-01-25 22:26 ` H. Peter Anvin
  0 siblings, 1 reply; 39+ messages in thread
From: Ian S. Nelson @ 2001-01-25 21:46 UTC (permalink / raw)
  To: linux-kernel@vger.kernel.org


I'm curious.  Why does Linux make that friendly 98/9a/88 looking
postcode pattern when it's running?  DOS and DOS95 don't do that.

I'm begining to feel like I can tell the system health by observing it,
kind of like "seeing the matrix."

Ian

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^ permalink raw reply	[flat|nested] 39+ messages in thread
* Re: Linux Post codes during runtime, possibly OT
@ 2001-01-26 15:41 Petr Vandrovec
  2001-01-26 15:07 ` Richard B. Johnson
  0 siblings, 1 reply; 39+ messages in thread
From: Petr Vandrovec @ 2001-01-26 15:41 UTC (permalink / raw)
  To: Richard B. Johnson; +Cc: Matthew Dharm, H. Peter Anvin, linux-kernel

On 26 Jan 01 at 8:58, Richard B. Johnson wrote:
> On Thu, 25 Jan 2001, H. Peter Anvin wrote:
> > > You could use the DMA scratch register at 0x19. I'm sure Linux doesn't
> > > "save" stuff there when setting up the DMA controller.
> > > 
> I will change the port on my machines and run them for a week. I
> don't have any DEC Rainbows or other such. Yes, I know Linux will
> not run on a '286.
> 
> Since 0x19 is a hardware register in a DMA controller, specifically
> called a "scratch" register, it is unlikely to hurt anything. Note
> that the BIOS saves stuff in CMOS. It never expects hardware registers
> to survive a "warm boot". It even checks in CMOS to see if it should
> preserve RAM.

Unless there are chips which need DELAY between accesses to DMA 
controller ;-) And I'm sure there are such. Also, if DMA controller
is integrated on board, outb is done in different speed than ISA 
forwarded cycle to postcode port.

Just in case, on my VIA, 1e6 outb(0,0x80) tooks 2.07s, 1e6 outb(0,0x19)
tooks 2.33s - so there is definitely difference - although in other 
direction than I expected. (What you can expect from this ....)
                                            Petr Vandrovec
                                            vandrove@vc.cvut.cz
                                            
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^ permalink raw reply	[flat|nested] 39+ messages in thread
* Re: Linux Post codes during runtime, possibly OT
@ 2001-01-26 15:42 Manfred Spraul
  2001-01-26 16:07 ` Richard B. Johnson
  0 siblings, 1 reply; 39+ messages in thread
From: Manfred Spraul @ 2001-01-26 15:42 UTC (permalink / raw)
  To: rjohnson, linux-kernel

> + * 
> + * Changed the slow-down I/O port from 0x80 to 0x19. 0x19 is a 
> + * DMA controller scratch register. rjohnson@analogic.com 
>    */ 
>  
What about making that a config option?

default: delay with 'outb 0x80', other options could be
	udelay(n); (n=1,2,3)
	outb 0x19

0x80 is a safe port, and IMHO changing the port on all i386 systems
because it's needed for some embedded system debuggers is too dangerous.

--
	Manfred
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^ permalink raw reply	[flat|nested] 39+ messages in thread

end of thread, other threads:[~2001-01-30 18:45 UTC | newest]

Thread overview: 39+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2001-01-25 21:46 Linux Post codes during runtime, possibly OT Ian S. Nelson
2001-01-25 22:26 ` H. Peter Anvin
2001-01-25 22:31   ` Matthew Dharm
2001-01-25 22:32     ` H. Peter Anvin
2001-01-25 22:41       ` Matthew Dharm
2001-01-25 22:45         ` H. Peter Anvin
2001-01-25 23:08       ` Richard B. Johnson
2001-01-25 23:10         ` H. Peter Anvin
2001-01-26 13:58           ` Richard B. Johnson
2001-01-26 16:19             ` H. Peter Anvin
2001-01-26 17:54               ` David Welch
2001-01-29  2:35               ` Paul Gortmaker
2001-01-27 10:20   ` Rogier Wolff
2001-01-27 20:47     ` H. Peter Anvin
2001-01-27 21:01       ` Rogier Wolff
2001-01-27 21:24         ` H. Peter Anvin
2001-01-28 10:12           ` Rogier Wolff
2001-01-28 10:18             ` H. Peter Anvin
2001-01-28 11:03               ` Rogier Wolff
2001-01-28 17:22               ` Jamie Lokier
2001-01-28 22:34               ` Pavel Machek
2001-01-29 15:09                 ` Richard B. Johnson
2001-01-29 19:21                 ` H. Peter Anvin
2001-01-28 22:29         ` Pavel Machek
2001-01-30 17:44         ` Mark H. Wood
2001-01-30 18:10           ` Richard B. Johnson
2001-01-30 18:16           ` mirabilos
2001-01-30 18:36             ` Richard B. Johnson
2001-01-30 18:41               ` mirabilos
  -- strict thread matches above, loose matches on Subject: below --
2001-01-26 15:41 Petr Vandrovec
2001-01-26 15:07 ` Richard B. Johnson
2001-01-26 15:15   ` Mark Hahn
2001-01-26 15:31     ` Jamie Lokier
2001-01-26 16:03       ` Richard B. Johnson
2001-01-26 16:22         ` Jamie Lokier
2001-01-26 15:42 Manfred Spraul
2001-01-26 16:07 ` Richard B. Johnson
2001-01-26 16:33   ` Brian Gerst
2001-01-27 12:28     ` Pavel Machek

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