Fix support for RAM-less multi-processor init

Fix regression after commit:
  7dfe32c540

Only align 16-bit entry on platforms that really require it,
indicated by selecting SIPI_VECTOR_IN_ROM in CPU Kconfig.
Disable assertion test of AP_SIPI_VECTOR for platforms not
depending on this feature.

Build of romstage should be fixed to get the vector address from
bootblock build automatically.

Change-Id: Ide470833c0254df1a9ff708369ab1c095ccfb98d
Signed-off-by: Kyösti Mälkki <kyosti.malkki@gmail.com>
Reviewed-on: http://review.coreboot.org/875
Tested-by: build bot (Jenkins)
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>

src/arch/x86/Kconfig

@@ -8,6 +8,13 @@ config AP_IN_SIPI_WAIT
 	default n
 	depends on ARCH_X86
 
+# Aligns 16bit entry code in bootblock so that hyper-threading CPUs
+# can boot AP CPUs to enable their shared caches.
+config SIPI_VECTOR_IN_ROM
+	bool
+	default n
+	depends on ARCH_X86
+
 config RAMBASE
 	hex
 	default 0x100000

src/arch/x86/init/ldscript_failover.lb

@@ -30,10 +30,11 @@ TARGET(binary)
 SECTIONS
 {
 	/* Symbol ap_sipi_vector must be aligned to 4kB to start AP CPUs
-	 * with Startup IPI message without RAM.
+	 * with Startup IPI message without RAM. Align .rom to next 4 byte
+	 * boundary anyway, so no pad byte appears between _rom and _start.
 	 */
 	.bogus ROMLOC_MIN : {
-		. = ALIGN(4096);
+		. = CONFIG_SIPI_VECTOR_IN_ROM ?	ALIGN(4096) : ALIGN(4);
 		ROMLOC = .;
 	} >rom = 0xff
 
@@ -52,11 +53,14 @@ SECTIONS
 	 * may cause the total size of a section to change when the start
 	 * address gets applied.
 	 */
-	ROMLOC_MIN = 0xffffff00 - (_erom - _rom + 16) - 4096;
+	ROMLOC_MIN = 0xffffff00 - (_erom - _rom + 16) -
+		(CONFIG_SIPI_VECTOR_IN_ROM ? 4096 : 0);
 
 	/* Post-check proper SIPI vector. */
-	_bogus = ASSERT(((ap_sipi_vector & 0x0fff) == 0x0), "Bad SIPI vector alignment");
+	_bogus = ASSERT(!CONFIG_SIPI_VECTOR_IN_ROM || ((ap_sipi_vector & 0x0fff) == 0x0),
-	_bogus = ASSERT((ap_sipi_vector == CONFIG_AP_SIPI_VECTOR), "Address mismatch on AP_SIPI_VECTOR");
+		"Bad SIPI vector alignment");
+	_bogus = ASSERT(!CONFIG_SIPI_VECTOR_IN_ROM || (ap_sipi_vector == CONFIG_AP_SIPI_VECTOR),
+		"Address mismatch on AP_SIPI_VECTOR");
 
 	/DISCARD/ : {
 		*(.comment)

src/cpu/intel/socket_mPGA604/Kconfig

@@ -11,6 +11,7 @@ config SOCKET_SPECIFIC_OPTIONS # dummy
 	select MMX
 	select SSE
 	select UDELAY_TSC
+	select SIPI_VECTOR_IN_ROM
 
 # mPGA604 are usually Intel Netburst CPUs which should have SSE2
 # but the ramtest.c code on the Dell S1850 seems to choke on