x86: Fix earlyprintk=dbgp for machines without NX

Jan Beulich · Ingo Molnar · commit 47d25003cbd9 · 2009-08-29T15:47:32.000+02:00
Since parse_early_param() may (e.g. for earlyprintk=dbgp)
involve calls to page table manipulation functions (here
set_fixmap_nocache()), NX hardware support must be determined
before calling that function (so that __supported_pte_mask gets
properly set up).

But the call after parse_early_param() can also not go away, as
that will honor eventual command line specified disabling of
the NX functionality.

( This will then just result in whatever mappings got
  established during parse_early_param() having the NX bit set
  despite it being disabled on the command line, but I think
  that's tolerable).

Signed-off-by: Jan Beulich &lt;jbeulich@novell.com&gt;
Cc: Yinghai Lu &lt;yhlu.kernel@gmail.com&gt;
LKML-Reference: &lt;4A97F3BD02000078000121B9@vpn.id2.novell.com&gt;
[ merged to x86/pat to resolve a conflict. ]
Signed-off-by: Ingo Molnar &lt;mingo@elte.hu&gt;
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
@@ -714,6 +714,16 @@ void __init setup_arch(char **cmdline_p)
 	strlcpy(command_line, boot_command_line, COMMAND_LINE_SIZE);
 	*cmdline_p = command_line;
 
+#ifdef CONFIG_X86_64
+	/*
+	 * Must call this twice: Once just to detect whether hardware doesn't
+	 * support NX (so that the early EHCI debug console setup can safely
+	 * call set_fixmap(), and then again after parsing early parameters to
+	 * honor the respective command line option.
+	 */
+	check_efer();
+#endif
+
 	parse_early_param();
 
 	/* VMI may relocate the fixmap; do this before touching ioremap area */
