2007-03-05 Till Straumann <strauman@slac.stanford.edu>

	* start/start.S, startup/bspstart.c: disable memory-select
	errors early (in start.S) to avoid hangs due to speculative
	memory access (motload maps absent memory in TLBs).
	Remove TLB mappings for which no physical memory is installed
	(bspstart). Enable HID1[RFXE] so that 'core_fault_in' errors
	result in a machine-check rather than stalling the machine.
	Re-enable memory-select errors at this point.

1 files changed, 48 insertions, 13 deletions

diff --git a/c/src/lib/libbsp/powerpc/mvme3100/startup/bspstart.c b/c/src/lib/libbsp/powerpc/mvme3100/startup/bspstart.c
index c5486abf34..9451062680 100644
--- a/c/src/lib/libbsp/powerpc/mvme3100/startup/bspstart.c
+++ b/c/src/lib/libbsp/powerpc/mvme3100/startup/bspstart.c
@@ -27,6 +27,7 @@
 #include <rtems/bspIo.h>
 #include <libcpu/spr.h>
 #include <libcpu/io.h>
+#include <libcpu/e500_mmu.h>
 #include <bsp/uart.h> 
 #include <bsp/irq.h> 
 #include <bsp/pci.h> 
@@ -38,6 +39,8 @@
 #define SHOW_MORE_INIT_SETTINGS
 #undef  DEBUG
 
+#define NumberOf(arr) (sizeof(arr)/sizeof(arr[0]))
+
 #ifdef  DEBUG
 #define STATIC
 #else
@@ -234,13 +237,15 @@ SPR_RW(HID1)
 
 void bsp_start( void )
 {
-unsigned char      *stack;
-register uint32_t  intrStack;
-register uint32_t  *intrStackPtr;
-unsigned char      *work_space_start;
-char               *chpt;
-ppc_cpu_id_t       myCpu;
-ppc_cpu_revision_t myCpuRevision;
+unsigned char       *stack;
+register uint32_t   intrStack;
+register uint32_t   *intrStackPtr;
+unsigned char       *work_space_start;
+char                *chpt;
+ppc_cpu_id_t        myCpu;
+ppc_cpu_revision_t  myCpuRevision;
+int                 i;
+E500_tlb_va_cache_t *tlb;
 
 VpdBufRec          vpdData [] = {
 	{ key: ProductIdent, instance: 0, buf: BSP_productIdent, buflen: sizeof(BSP_productIdent) - 1 },
@@ -321,13 +326,45 @@ VpdBufRec          vpdData [] = {
 	printk("Going to start PCI buses scanning and initialization\n");
 #endif
 
+	BSP_mem_size            = BSP_get_mem_size();
+
 	{
-		/* disable checking for memory-select errors */
-		*(volatile uint32_t*)0xe1002e44 |= 1;
-		/* clear all pending errors */
-		*(volatile uint32_t*)0xe1002e40  = 0xffffffff;
+		/* memory-select errors were disabled in 'start.S';
+		 * motload has all TLBs mapping a possible larger area as
+		 * memory (not-guarded, caching-enabled) than actual physical
+		 * memory is available.
+		 * In case of speculative loads this may cause 'memory-select' errors
+		 * which seem to raise 'core_fault_in' (found no description in
+		 * the manual but I experienced this problem).
+		 * Such errors (if HID1[RFXE] is clear) may *stall* execution
+		 * leading to mysterious 'hangs'.
+		 *
+		 * Here we remove all mappings, re-enable memory-select
+		 * errors and make sure we enable HID1[RFXE] to avoid
+		 * stalls (since we don't implement handling individual
+		 * error-handling interrupts).
+		 */
+
 		/* enable machine check for bad bus errors */
 		_write_HID1( _read_HID1() | 0x20000 );
+
+		rtems_e500_initlb();
+
+		for ( i=0, tlb=rtems_e500_tlb_va_cache; i<NumberOf(rtems_e500_tlb_va_cache); i++, tlb++ ) {
+			/* disable TLBs for caching-enabled, non-guarded areas
+			 * beyond physical memory
+			 */
+			if (    tlb->att.v
+			    &&  0xa != (tlb->att.wimge & 0xa)
+				&&  (tlb->va.va_epn<<12) >= BSP_mem_size ) {
+				rtems_e500_clrtlb( E500_SELTLB_1 | i );
+			}
+		}
+
+		/* clear all pending memory errors */
+		_ccsr_wr32(0x2e40, 0xffffffff);
+		/* enable checking for memory-select errors */
+		_ccsr_wr32(0x2e44, _ccsr_rd32(0x2e44) & ~1 );
 	}
 
 	printk("Build Date: %s\n",BSP_build_date);
@@ -389,8 +426,6 @@ VpdBufRec          vpdData [] = {
 	_write_SPRG0(PPC_BSP_HAS_FIXED_PR288);
 #endif
 
-	BSP_mem_size            = BSP_get_mem_size();
-
 	if ( (chpt = strstr(BSP_commandline_string,"MEMSZ=")) ) {
 		char		*endp;
 		uint32_t 	sz;