linux-kernel - Re: linux-next: build failure after merge of the tip tree

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Message-ID: <CAJvTdKnoNh2YAvtXraYxTct+8e6e_8Om9cAZGSTpy8UO=t=W4w@mail.gmail.com>
Date:	Sun, 19 Jan 2014 23:45:43 -0500
From:	Len Brown <lenb@...nel.org>
To:	Stephen Rothwell <sfr@...b.auug.org.au>
Cc:	Peter Zijlstra <peterz@...radead.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	linux-next@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: linux-next: build failure after merge of the tip tree

+static void mwait_idle(void)
+{
+       mwait_idle_with_hints(0, 0);
+}
+

The reason the patch above will crash Core2 machines is because
core2 machines don't support mwait_idle_with_hints().

The calling sequence for old and new MWAIT instructions is different.
The former must be invoked with interrupts enabled,
and the later can be invoked with interrupts disabled,
which is a feature that Linux takes advantage of.

thanks,
-Len
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