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Date: Mon, 31 Dec 2007 17:38:43 +0800
From: Erich Dollansky <oceanare@pacific.net.sg>
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To: Kostik Belousov <kostikbel@gmail.com>
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Cc: Kip Macy <kip.macy@gmail.com>, Ivan Voras <ivoras@freebsd.org>,
	freebsd-hackers@freebsd.org
Subject: Re: Architectures with strict alignment?
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Hi,

Kostik Belousov wrote:
> On Sat, Dec 29, 2007 at 01:12:04PM +0200, Kostik Belousov wrote:
>> On Sat, Dec 29, 2007 at 12:14:11AM -0800, Kip Macy wrote:
> 
> I.e., it seems that gcc does not feel too guilty generating unaligned
> half-word writes on i386. :(

this should not be a problem inside a cache line.

If the access goes accross two cache lines and the other cache line is 
not in the cache, it becomes real difficult.

I can't tell you what the hardware actually does in this case.

It should read the second affected cache line into the cache. But what 
happens if the second affected cache line is blocked by another CPU 
while the current CPU blocks the first cache line?

Erich