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From: Zoltan Menyhart <Zoltan.Menyhart_AT_bull.net@nospam.org>
To: linux-ia64@vger.kernel.org
Subject: Re: [RFC] prevent "dd if=/dev/mem" crash
Date: Thu, 23 Oct 2003 09:31:53 +0000	[thread overview]
Message-ID: <marc-linux-ia64-106690168512047@msgid-missing> (raw)
In-Reply-To: <marc-linux-ia64-106642876514553@msgid-missing>

Some machines may require special memory zones, e.g. for ia64
architectures you need to keep the "minimal state save" area
for the Processor Abstraction Layer in un-cached memory.
If you read the memory "in the usual way" then you access the
memory through the HW caches.
The ia64 architecture forbids to have both cached and un-cached
access to the same memory location (by any of the CPUs, DMAs),
otherwise you create a cache paradox => machine check.
Think twice before even trying a "dd if=/dev/mem"...

Zoltan Menyhart

  parent reply	other threads:[~2003-10-23  9:31 UTC|newest]

Thread overview: 48+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-10-17 22:10 [RFC] prevent "dd if=/dev/mem" crash Bjorn Helgaas
2003-10-17 22:19 ` Luck, Tony
2003-10-17 22:23 ` Matt Mackall
2003-10-17 22:40 ` Andreas Schwab
2003-10-17 22:50 ` Andrew Morton
2003-10-17 23:25 ` Bjorn Helgaas
2003-10-17 23:55 ` Andrew Morton
2003-10-18  0:15 ` William Lee Irwin III
2003-10-18  0:21 ` David Mosberger
2003-10-18  0:49 ` Andrew Morton
2003-10-18  1:31 ` Matt Chapman
2003-10-18  1:41 ` Andrew Morton
2003-10-18  1:48 ` David Mosberger
2003-10-18  2:01 ` Andrew Morton
2003-10-18  2:01 ` Matt Chapman
2003-10-19 11:25 ` Eric W. Biederman
2003-10-19 18:17 ` Pavel Machek
2003-10-19 19:01 ` William Lee Irwin III
2003-10-20 15:17 ` Bjorn Helgaas
2003-10-20 17:42 ` Bjorn Helgaas
2003-10-20 18:48 ` David Mosberger
2003-10-23  8:33 ` Martin Pool
2003-10-23  9:31 ` Zoltan Menyhart [this message]
2003-10-23 21:05 ` Bjorn Helgaas
  -- strict thread matches above, loose matches on Subject: below --
2003-10-17 22:10 Bjorn Helgaas
2003-10-17 22:23 ` Matt Mackall
2003-10-17 22:50 ` Andrew Morton
2003-10-17 23:25   ` Bjorn Helgaas
2003-10-17 23:55     ` Andrew Morton
2003-10-18  0:15       ` William Lee Irwin III
2003-10-18  0:21       ` David Mosberger
2003-10-18  0:49         ` Andrew Morton
2003-10-18  1:31           ` Matt Chapman
2003-10-18  1:41             ` Andrew Morton
2003-10-18  1:48           ` David Mosberger
2003-10-18  2:01             ` Andrew Morton
2003-10-18  2:01             ` Matt Chapman
2003-10-19 11:25           ` Eric W. Biederman
2003-10-19 19:01             ` William Lee Irwin III
2003-10-20 15:17         ` Bjorn Helgaas
2003-10-20 18:48           ` David Mosberger
2003-10-20 17:42       ` Bjorn Helgaas
2003-10-23 21:05         ` Bjorn Helgaas
2003-10-19 18:17   ` Pavel Machek
2003-10-23  8:33     ` Martin Pool
2003-10-23  9:31       ` Zoltan Menyhart
2003-10-17 22:19 Luck, Tony
2003-10-17 22:40 ` Andreas Schwab

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