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From: Kim Phillips <kim.phillips@freescale.com>
To: "Keith Mund" <keith.mund@clearcube.com>
Cc: linuxppc-dev@ozlabs.org, u-boot-users@lists.sourceforge.net
Subject: Re: MPC83xx - previous patch to set MBAR
Date: Wed, 1 Aug 2007 19:20:09 -0500	[thread overview]
Message-ID: <20070801192009.656fc2e0.kim.phillips@freescale.com> (raw)
In-Reply-To: <5EACFDEA24DADE42BF109303D305A8093120A6@MAIL.clearcube.com>

On Wed, 1 Aug 2007 15:20:22 -0500
"Keith Mund" <keith.mund@clearcube.com> wrote:

> There was a u-boot 1.1.3 patch for start.S posted on the Freescale LTIB

posts concerning u-boot should go to the u-boot-users list (cc'd).

> site:
> http://www.bitshrine.org/gpp/u-boot-1.1.3-mpc83xx-cpu-4.patch
> 
> The end result simply adds a line to set MBAR to match IMMRBAR.
> 
>         lis     r3, CFG_IMMRBAR@h
>         ori     r3, r3, CFG_IMMRBAR@l
>         stw     r3, IMMRBAR(r4)
> +       mtspr   MBAR, r3
> 
> Are these patches routinely added to the mainstream u-boot code? 
> 
> Is there any reason why this fix is not a good idea?
> 
does setting MBAR really fix anything?

MBAR doesn't live up to its name.  It's a general-purpose scratch
register - the hardware doesn't do anything with it.  So, wrt integrity
within u-boot itself, I see no point/value in setting it.  If some
piece of software needs temporary storage, it can set it and use it as
it wishes, independent of u-boot.

Kim

WARNING: multiple messages have this Message-ID (diff)
From: Kim Phillips <kim.phillips@freescale.com>
To: u-boot@lists.denx.de
Subject: [U-Boot-Users] MPC83xx - previous patch to set MBAR
Date: Wed, 1 Aug 2007 19:20:09 -0500	[thread overview]
Message-ID: <20070801192009.656fc2e0.kim.phillips@freescale.com> (raw)
In-Reply-To: <5EACFDEA24DADE42BF109303D305A8093120A6@MAIL.clearcube.com>

On Wed, 1 Aug 2007 15:20:22 -0500
"Keith Mund" <keith.mund@clearcube.com> wrote:

> There was a u-boot 1.1.3 patch for start.S posted on the Freescale LTIB

posts concerning u-boot should go to the u-boot-users list (cc'd).

> site:
> http://www.bitshrine.org/gpp/u-boot-1.1.3-mpc83xx-cpu-4.patch
> 
> The end result simply adds a line to set MBAR to match IMMRBAR.
> 
>         lis     r3, CFG_IMMRBAR at h
>         ori     r3, r3, CFG_IMMRBAR at l
>         stw     r3, IMMRBAR(r4)
> +       mtspr   MBAR, r3
> 
> Are these patches routinely added to the mainstream u-boot code? 
> 
> Is there any reason why this fix is not a good idea?
> 
does setting MBAR really fix anything?

MBAR doesn't live up to its name.  It's a general-purpose scratch
register - the hardware doesn't do anything with it.  So, wrt integrity
within u-boot itself, I see no point/value in setting it.  If some
piece of software needs temporary storage, it can set it and use it as
it wishes, independent of u-boot.

Kim

  reply	other threads:[~2007-08-02  0:20 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2007-08-01 13:30 [2.6 patch] ppc .gitignore update Adrian Bunk
2007-08-01 13:53 ` Grant Likely
2007-08-01 13:53   ` Grant Likely
2007-08-01 19:06   ` Adrian Bunk
2007-08-01 19:06     ` Adrian Bunk
2007-08-01 20:20   ` MPC83xx - previous patch to set MBAR Keith Mund
2007-08-02  0:20     ` Kim Phillips [this message]
2007-08-02  0:20       ` [U-Boot-Users] " Kim Phillips
2007-08-02  2:14       ` Liu Dave-r63238
2007-08-02  2:14         ` Liu Dave-r63238
2007-08-02  2:34         ` Alfred Manheim
2007-08-02  2:34           ` Alfred Manheim
2007-08-02 15:28         ` Scott Wood
2007-08-02 15:28           ` Scott Wood
2007-08-02 16:12           ` Kumar Gala
2007-08-02 16:12             ` Kumar Gala

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