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From: Wolfgang Denk <wd@denx.de>
To: u-boot@lists.denx.de
Subject: [U-Boot] ELF_RELOC causes strange I-cache issues
Date: Wed, 20 Oct 2010 22:54:01 +0200	[thread overview]
Message-ID: <20101020205401.39B4D1359B3@gemini.denx.de> (raw)
In-Reply-To: <4CBF4D17.6020403@free.fr>

Dear Albert ARIBAUD,

In message <4CBF4D17.6020403@free.fr> you wrote:
>
> Is the data cache on or off when you experience the issue? If it was on,

DC is always off.  DC on has always casued problems with lots of
drivers, including USB, so we never attempted doing that (except for
verification that it indeed does cause problems).

> can you try with data cache off and instruction cache on?

Done. The situation was IC off/DC off versus IC on/DC off.

> If the issue arises when both caches are on, then *maybe* the issue is
> caused by code which was loaded into i-cache *before* it was fixed up,
> or loaded while its fixups were still in the data cache. However this
> does not explain everything, since even with instruction cache off, data
> cache can hold fixups for some time and thus non-cached instruction
> fetches could return the wrong code.

As mentioned, DC has always been off.

> Still, since ELF fixups are some sort of code self-modification, they
> must, according to the ARM doc, be followed by an IMB sequence. The
> exact sequence varies; I will look up and provide the sequence for
> ARM1136 tomorrow -- unless someone else can do it sooner, of course.

Thanks.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Lots of people drink from the wrong bottle sometimes.
	-- Edith Keeler, "The City on the Edge of Forever",
	   stardate unknown

  reply	other threads:[~2010-10-20 20:54 UTC|newest]

Thread overview: 26+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-10-20 18:49 [U-Boot] ELF_RELOC causes strange I-cache issues Wolfgang Denk
2010-10-20 20:12 ` Albert ARIBAUD
2010-10-20 20:54   ` Wolfgang Denk [this message]
2010-10-20 22:20     ` Joakim Tjernlund
2010-10-21  9:18     ` Albert Aribaud
2010-10-21  9:51       ` Heiko Schocher
2010-10-21 10:11         ` Reinhard Meyer
2010-10-21 10:34           ` Albert ARIBAUD
2010-10-21 10:49             ` Reinhard Meyer
2010-10-21 10:50             ` Heiko Schocher
2010-10-21 11:03             ` Stefan Roese
2010-10-21 10:54           ` Wolfgang Denk
2010-10-21 10:56         ` Albert ARIBAUD
2010-10-21 11:36           ` Wolfgang Denk
2010-10-21 11:45             ` Wolfgang Denk
2010-10-21 11:52               ` Stefano Babic
2010-10-21 11:53           ` Wolfgang Denk
2010-10-21 12:00           ` Wolfgang Denk
2010-10-21 12:53             ` Albert ARIBAUD
2010-10-21 11:28         ` Joakim Tjernlund
2010-10-21 10:05       ` Wolfgang Denk
2010-10-22 12:23 ` [U-Boot] [PATCH] ehci-hcd.c: fix hanging under higher load Wolfgang Denk
2010-10-22 19:51   ` Remy Bohmer
2010-10-22 12:26 ` [U-Boot] ELF_RELOC causes strange I-cache issues Wolfgang Denk
2010-10-22 13:19   ` Albert ARIBAUD
2010-10-22 13:28     ` Wolfgang Denk

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