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From: Ralf Baechle <ralf@linux-mips.org>
To: Shinya Kuribayashi <shinya.kuribayashi@necel.com>
Cc: Wu Zhangjin <wuzhangjin@gmail.com>, Greg KH <gregkh@suse.de>,
	linux-mips@linux-mips.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 1/3] Loongson-2F: Flush the branch target history such as BTB and RAS
Date: Thu, 11 Mar 2010 10:59:44 +0100	[thread overview]
Message-ID: <20100311095944.GC18065@linux-mips.org> (raw)
In-Reply-To: <4B98632E.70806@necel.com>

On Thu, Mar 11, 2010 at 12:27:42PM +0900, Shinya Kuribayashi wrote:

> Are you sure that RAS represents "Row Address Strobe", not "Return
> Address Stack?"
> 
> By the way, we have a similar local workaround for vr55xx processors
> when switching from kernel mode to user mode.  It's not necessarily
> related to out-of-order issues, but we need to prevent the processor
> from doing instruction prefetch beyond "eret" instruction.

Some R4000 revisions may do silly things in case of an NMI where c0_errorepc
is pointing is pointing to an ERET instruction.

There are various processors which want to save and restore core-specific
registers, for example the Cavium cnMIPS core.

> In the long term, it would be appreciated that the kernel has a set
> of hooks when switching KUX-modes, so that each machine could have
> his own, processor-specific treatmens.

It seems that uasm is the tool of choice.

  Ralf

  parent reply	other threads:[~2010-03-11 10:00 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-03-09 17:12 [PATCH 0/3] Workaround the Out-of-order Issue of Loongson-2F Wu Zhangjin
2010-03-09 17:12 ` [PATCH 1/3] Loongson-2F: Flush the branch target history such as BTB and RAS Wu Zhangjin
2010-03-10 10:44   ` Sergei Shtylyov
2010-03-10 15:24     ` Wu Zhangjin
2010-03-11  3:27   ` Shinya Kuribayashi
2010-03-11  3:35     ` Wu Zhangjin
2010-03-11  9:59     ` Ralf Baechle [this message]
2010-03-13  3:52       ` Wu Zhangjin
2010-03-14 23:42         ` Shinya Kuribayashi
2010-03-09 17:12 ` [PATCH 2/3] Loongson-2F: Enable fixups of binutils 2.20.1 Wu Zhangjin
2010-03-09 17:12 ` [PATCH 3/3] Loongson-2F: Fixup of problems introduced by -mfix-loongson2f-jump " Wu Zhangjin

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