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Re: Memory corruption

To: Warner Losh <imp@village.org>
Subject: Re: Memory corruption
From: "William J. Earl" <wje@fir.engr.sgi.com>
Date: Wed, 7 Jul 1999 20:12:03 -0700 (PDT)
Cc: "Harald Koerfgen" <Harald.Koerfgen@home.ivm.de>, Ralf Baechle <ralf@uni-koblenz.de>, linux-mips@vger.rutgers.edu, linux-mips@fnet.fr, linux@cthulhu.engr.sgi.com, Ulf Carlsson <ulfc@thepuffingroup.com>, "William J. Earl" <wje@fir.engr.sgi.com>
In-reply-to: <199907080151.TAA05482@harmony.village.org>
References: <XFMail.990707230857.Harald.Koerfgen@home.ivm.de> <199907080151.TAA05482@harmony.village.org>
Sender: owner-linux@cthulhu.engr.sgi.com
Warner Losh writes:
 > In message <XFMail.990707230857.Harald.Koerfgen@home.ivm.de> Harald Koerfgen 
 > writes:
 > : That's definitely true for R3k DECstations, and no, flushing the icache in
 > : flush_tlb_page() does not help. I have added cacheflushing to all tlb 
 > routines,
 > : copy_page and even rw_swap_page_base() and swap_after_unlock_page() without
 > : success.
 > 
 > Don'y you want to flush the dcache as well?  I think that you can run
 > into problems when you have a dirty dcache and then dma into the pages
 > that are dirty.  Instant karma corruption, no?  Or am I thinking of
 > some other problem?

      The R3000 has a write-through cache, so there cannot be dirty cache
lines, although you do have to flush the write buffers to be completely
correct (in the case of a DMA device writing to memory VERY quickly after
the register write which starts it up, on some hardware). 

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