linux-kernel - RE: [PATCH 2/9] x86: introduce a set of platform feature flags

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Date:	Thu, 2 Jul 2009 16:09:09 -0700
From:	"Pan, Jacob jun" <jacob.jun.pan@...el.com>
To:	Pavel Machek <pavel@....cz>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"H. Peter Anvin" <hpa@...ux.intel.com>
Subject: RE: [PATCH 2/9] x86: introduce a set of platform feature flags

>> +#define platform_has(bit) \
>> +	test_bit(bit, (unsigned long *)platform_feature)
>
>test_bit and friends imply synchronization you probably  don't want or
>need...
>
[[JPAN]] could you explain a little more? The disassembly shows the test_bit
ends up as a testb instruction and a jump. Why there is synchronization
 involved?
Perhaps on some architectures?
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