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Message-Id: <200901202148.n0KLmFqx044467@www.freebsd.org>
Date: Tue, 20 Jan 2009 21:48:15 GMT
From: Daniel Tourde <daniel.tourde@caelae.se>
To: freebsd-gnats-submit@FreeBSD.org
Subject: hw.ata.ata_dma_limit without any effect 
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>Number:         130794
>Category:       kern
>Synopsis:       [ata] hw.ata.ata_dma_limit without any effect
>Confidential:   no
>Severity:       non-critical
>Priority:       medium
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:  
>Class:          sw-bug
>Submitter-Id:   current-users
>Arrival-Date:   Tue Jan 20 21:50:03 UTC 2009
>Closed-Date:    
>Last-Modified:  Wed Jan 21 18:50:01 UTC 2009
>Originator:     Daniel Tourde
>Release:        7.1
>Organization:
>Environment:
FreeBSD 7.1-RELEASE #0 GENERIC amd64
>Description:
Hi!

I need to slow down the UDMA on my Hard Drive. It is set automatically to UDMA133 which causes a lot of warnings and if I bring it to UDMA100, the warning and the error messages disappear.

To do so, 2 options:
- The inelegant: atacontrol mode ad0 UDMA5
- The elegant: put hw.ata.ata_dma_limit="5" in loader.conf

I am very tempted by the elegant solution but unfortunately it does not work. It has absolutely no effect whatsoever... :(

sysctl hw.ata.ata_dma_limit="5" gives
sysctl: unknown oid 'hw.ata.ata_dma_limit'

I think it is a bug...

Daniel
>How-To-Repeat:

>Fix:


>Release-Note:
>Audit-Trail:

From: Daniel Tourde <daniel.tourde@caelae.se>
To: bug-followup@freebsd.org,
 daniel.tourde@caelae.se
Cc:  
Subject: Re: misc/130794: hw.ata.ata_dma_limit without any effect
Date: Tue, 20 Jan 2009 23:23:11 +0100

 Well,
 
 I need to complement a bit what I wrote.
 I had seen a bug report with a patch from May 2008 (kern/123980) proposing to 
 create this new 'flag': hw.ata.ata_dma_limit and I had understood first that 
 it had been included into 7.1. Therefore the wording of my bug report...
 
 I checked the source code and it turns out that the patch has never been 
 applied, so the option simply does not exist.
 
 This leaves me with my present problem: warnings and errors ( WARNING - 
 READ_DMA UDMA ICRC error) caused by either a corrupted 80 pins cable or a 
 problem within the kernel.
 
 		Daniel

From: Daniel Tourde <daniel.tourde@caelae.se>
To: bug-followup@freebsd.org,
 daniel.tourde@caelae.se
Cc:  
Subject: Re: kern/130794: [ata] hw.ata.ata_dma_limit without any effect
Date: Wed, 21 Jan 2009 19:46:26 +0100

 Hi!
 
 I replaced the cable with a new shorter one (about 2 inches shorter) and I 
 still have the  WARNING -  READ_DMA UDMA ICRC error... :(
 
 I am planning now to apply the patch provided in kern/123980.
 
 		Daniel
>Unformatted:
