ACPI: delete the "acpi=ht" boot option

acpi=ht was important in 2003 -- before ACPI was
universally deployed and enabled by default in
the major Linux distributions.

At that time, there were a fair number of people who
or chose to, or needed to, run with acpi=off,
yet also wanted access to Hyper-threading.

Today we find that many invocations of "acpi=ht"
are accidental, and thus is it possible that it
is doing more harm than good.

In 2.6.34, we warn on invocation of acpi=ht.
In 2.6.35, we delete the boot option.

Signed-off-by: Len Brown <[e-mail]>

Documentation/kernel-parameters.txt

···
 
 	acpi=		[HW,ACPI,X86]
 			Advanced Configuration and Power Interface
-			Format: { force | off | ht | strict | noirq | rsdt }
+			Format: { force | off | strict | noirq | rsdt }
 			force -- enable ACPI if default was off
 			off -- disable ACPI if default was on
 			noirq -- do not use ACPI for IRQ routing
-			ht -- run only enough ACPI to enable Hyper Threading
 			strict -- Be less tolerant of platforms that are not
 				strictly ACPI specification compliant.
 			rsdt -- prefer RSDT over (default) XSDT

arch/ia64/include/asm/acpi.h

···
 #define acpi_noirq 0	/* ACPI always enabled on IA64 */
 #define acpi_pci_disabled 0 /* ACPI PCI always enabled on IA64 */
 #define acpi_strict 1	/* no ACPI spec workarounds on IA64 */
-#define acpi_ht 0	/* no HT-only mode on IA64 */
 #endif
 #define acpi_processor_cstate_check(x) (x) /* no idle limits on IA64 :) */
 static inline void disable_acpi(void) { }

arch/x86/include/asm/acpi.h

···
 extern int acpi_noirq;
 extern int acpi_strict;
 extern int acpi_disabled;
-extern int acpi_ht;
 extern int acpi_pci_disabled;
 extern int acpi_skip_timer_override;
 extern int acpi_use_timer_override;
···
 static inline void disable_acpi(void)
 {
 	acpi_disabled = 1;
-	acpi_ht = 0;
 	acpi_pci_disabled = 1;
 	acpi_noirq = 1;
 }

arch/x86/kernel/acpi/boot.c

···
 int acpi_noirq;				/* skip ACPI IRQ initialization */
 int acpi_pci_disabled;		/* skip ACPI PCI scan and IRQ initialization */
 EXPORT_SYMBOL(acpi_pci_disabled);
-int acpi_ht __initdata = 1;	/* enable HT */
 
 int acpi_lapic;
 int acpi_ioapic;
···
 
 	/*
 	 * If acpi_disabled, bail out
-	 * One exception: acpi=ht continues far enough to enumerate LAPICs
 	 */
-	if (acpi_disabled && !acpi_ht)
+	if (acpi_disabled)
 		return; 
 
 	/*
···
 {
 	/*
 	 * If acpi_disabled, bail out
-	 * One exception: acpi=ht continues far enough to enumerate LAPICs
 	 */
-	if (acpi_disabled && !acpi_ht)
+	if (acpi_disabled)
 		return 1;
 
 	/*
···
 
 	/*
 	 * If acpi_disabled, bail out
-	 * One exception: acpi=ht continues far enough to enumerate LAPICs
 	 */
-	if (acpi_disabled && !acpi_ht)
+	if (acpi_disabled)
 		return 1;
 
 	acpi_table_parse(ACPI_SIG_BOOT, acpi_parse_sbf);
···
 	/* acpi=force to over-ride black-list */
 	else if (strcmp(arg, "force") == 0) {
 		acpi_force = 1;
-		acpi_ht = 1;
 		acpi_disabled = 0;
 	}
 	/* acpi=strict disables out-of-spec workarounds */
 	else if (strcmp(arg, "strict") == 0) {
 		acpi_strict = 1;
-	}
-	/* Limit ACPI just to boot-time to enable HT */
-	else if (strcmp(arg, "ht") == 0) {
-		if (!acpi_force) {
-			printk(KERN_WARNING "acpi=ht will be removed in Linux-2.6.35\n");
-			disable_acpi();
-		}
-		acpi_ht = 1;
 	}
 	/* acpi=rsdt use RSDT instead of XSDT */
 	else if (strcmp(arg, "rsdt") == 0) {

arch/x86/lguest/boot.c

···
 #endif
 #ifdef CONFIG_ACPI
 	acpi_disabled = 1;
-	acpi_ht = 0;
 #endif
 
 	/*

drivers/acpi/tables.c

···
 	unsigned long table_end;
 	acpi_size tbl_size;
 
-	if (acpi_disabled && !acpi_ht)
+	if (acpi_disabled)
 		return -ENODEV;
 
 	if (!handler)
···
 	struct acpi_table_header *table = NULL;
 	acpi_size tbl_size;
 
-	if (acpi_disabled && !acpi_ht)
+	if (acpi_disabled)
 		return -ENODEV;
 
 	if (!handler)