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[Xen-changelog] By default do not enable local APIC if disabled by the BIOS. This



ChangeSet 1.1599, 2005/05/30 22:15:54+01:00, kaf24@xxxxxxxxxxxxxxxxxxxx

        By default do not enable local APIC if disabled by the BIOS. This
        matches Linux behaviour and ought to improve stability on buggy
        hardware/firmware (laptops in particular). As in Linux, you can
        forcibly enable the APIC with 'lapic' command-line option, or
        forcibly ignore it with 'nolapic'.
        Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>



 docs/src/user.tex            |   26 ++++++++++++++-------
 xen/arch/x86/apic.c          |   51 ++++++++++++++++++++++++++++++++++++++++++-
 xen/arch/x86/genapic/probe.c |   36 ++++++++++--------------------
 xen/arch/x86/setup.c         |   19 ++--------------
 4 files changed, 83 insertions(+), 49 deletions(-)


diff -Nru a/docs/src/user.tex b/docs/src/user.tex
--- a/docs/src/user.tex 2005-05-30 18:02:07 -04:00
+++ b/docs/src/user.tex 2005-05-30 18:02:07 -04:00
@@ -1770,14 +1770,25 @@
  Select the CPU scheduler Xen should use.  The current
  possibilities are `bvt' (default), `atropos' and `rrobin'. 
  For more information see Section~\ref{s:sched}. 
-\end{description} 
 
-In addition, the following platform-specific options may be specified
-on the Xen command line. Since domain 0 shares responsibility for
-booting the platform, Xen will automatically propagate these options
-to its command line.
+\item [apic\_verbosity=debug,verbose ]
+ Print more detailed information about local APIC and IOAPIC configuration.
+
+\item [lapic ]
+ Force use of local APIC even when left disabled by uniprocessor BIOS.
+
+\item [nolapic ]
+ Ignore local APIC in a uniprocessor system, even if enabled by the BIOS.
+
+\item [apic=bigsmp,default,es7000,summit ]
+ Specify NUMA platform. This can usually be probed automatically.
 
-These options are taken from Linux's command-line syntax with
+\end{description} 
+
+In addition, the following options may be specified on the Xen command
+line. Since domain 0 shares responsibility for booting the platform,
+Xen will automatically propagate these options to its command
+line. These options are taken from Linux's command-line syntax with
 unchanged semantics.
 
 \begin{description}
@@ -1791,9 +1802,6 @@
 \item [noapic ]
  Instruct Xen (and domain 0) to ignore any IOAPICs that are present in
  the system, and instead continue to use the legacy PIC.
-
-\item [apic=debug,verbose ]
- Print more detailed information about local APIC and IOAPIC configuration.
 
 \end{description} 
 
diff -Nru a/xen/arch/x86/apic.c b/xen/arch/x86/apic.c
--- a/xen/arch/x86/apic.c       2005-05-30 18:02:07 -04:00
+++ b/xen/arch/x86/apic.c       2005-05-30 18:02:07 -04:00
@@ -99,6 +99,13 @@
         apic_write_around(APIC_LVTPC, v | APIC_LVT_MASKED);
     }
 
+/* lets not touch this if we didn't frob it */
+#ifdef CONFIG_X86_MCE_P4THERMAL
+    if (maxlvt >= 5) {
+        v = apic_read(APIC_LVTTHMR);
+        apic_write_around(APIC_LVTTHMR, v | APIC_LVT_MASKED);
+    }
+#endif
     /*
      * Clean APIC state for other OSs:
      */
@@ -110,6 +117,10 @@
     if (maxlvt >= 4)
         apic_write_around(APIC_LVTPC, APIC_LVT_MASKED);
 
+#ifdef CONFIG_X86_MCE_P4THERMAL
+    if (maxlvt >= 5)
+        apic_write_around(APIC_LVTTHMR, APIC_LVT_MASKED);
+#endif
     v = GET_APIC_VERSION(apic_read(APIC_LVR));
     if (APIC_INTEGRATED(v)) {  /* !82489DX */
         if (maxlvt > 3)        /* Due to Pentium errata 3AP and 11AP. */
@@ -134,6 +145,7 @@
         outb(0x70, 0x22);
         outb(0x01, 0x23);
     }
+    enable_apic_mode();
 }
 
 void disconnect_bsp_APIC(void)
@@ -448,20 +460,45 @@
  * Original code written by Keir Fraser.
  */
 
+/*
+ * Knob to control our willingness to enable the local APIC.
+ */
+int enable_local_apic __initdata = 0; /* -1=force-disable, +1=force-enable */
+
+static void __init lapic_disable(char *str)
+{
+    enable_local_apic = -1;
+    clear_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);
+}
+custom_param("nolapic", lapic_disable);
+
+static void __init lapic_enable(char *str)
+{
+    enable_local_apic = 1;
+}
+custom_param("lapic", lapic_enable);
+
 static void __init apic_set_verbosity(char *str)
 {
     if (strcmp("debug", str) == 0)
         apic_verbosity = APIC_DEBUG;
     else if (strcmp("verbose", str) == 0)
         apic_verbosity = APIC_VERBOSE;
+    else
+        printk(KERN_WARNING "APIC Verbosity level %s not recognised"
+               " use apic_verbosity=verbose or apic_verbosity=debug", str);
 }
-custom_param("apic", apic_set_verbosity);
+custom_param("apic_verbosity", apic_set_verbosity);
 
 static int __init detect_init_APIC (void)
 {
     u32 h, l, features;
     extern void get_cpu_vendor(struct cpuinfo_x86*);
 
+    /* Disabled by kernel option? */
+    if (enable_local_apic < 0)
+        return -1;
+
     /* Workaround for us being called before identify_cpu(). */
     get_cpu_vendor(&boot_cpu_data);
 
@@ -482,6 +519,15 @@
 
     if (!cpu_has_apic) {
         /*
+         * Over-ride BIOS and try to enable the local
+         * APIC only if "lapic" specified.
+         */
+        if (enable_local_apic <= 0) {
+            printk("Local APIC disabled by BIOS -- "
+                   "you can enable it with \"lapic\"\n");
+            return -1;
+        }
+        /*
          * Some BIOSes disable the local APIC in the
          * APIC_BASE MSR. This can only be done in
          * software for Intel P6 or later and AMD K7
@@ -951,6 +997,9 @@
  */
 int __init APIC_init_uniprocessor (void)
 {
+    if (enable_local_apic < 0)
+        clear_bit(X86_FEATURE_APIC, boot_cpu_data.x86_capability);
+
     if (!smp_found_config && !cpu_has_apic)
         return -1;
 
diff -Nru a/xen/arch/x86/genapic/probe.c b/xen/arch/x86/genapic/probe.c
--- a/xen/arch/x86/genapic/probe.c      2005-05-30 18:02:07 -04:00
+++ b/xen/arch/x86/genapic/probe.c      2005-05-30 18:02:07 -04:00
@@ -19,7 +19,7 @@
 extern struct genapic apic_es7000;
 extern struct genapic apic_default;
 
-struct genapic *genapic = &apic_default;
+struct genapic *genapic;
 
 struct genapic *apic_probe[] __initdata = { 
        &apic_summit,
@@ -29,38 +29,28 @@
        NULL,
 };
 
-void __init generic_apic_probe(char *command_line) 
+static void __init genapic_apic_force(char *str)
+{
+       int i;
+       for (i = 0; apic_probe[i]; i++)
+               if (!strcmp(apic_probe[i]->name, str))
+                       genapic = apic_probe[i];
+}
+custom_param("apic", genapic_apic_force);
+
+void __init generic_apic_probe(void) 
 { 
-       char *s;
        int i;
-       int changed = 0;
+       int changed = (genapic != NULL);
 
-       s = strstr(command_line, "apic=");
-       if (s && (s == command_line || isspace(s[-1]))) { 
-               char *p = strchr(s, ' '), old; 
-               if (!p)
-                       p = strchr(s, '\0'); 
-               old = *p; 
-               *p = 0; 
-               for (i = 0; !changed && apic_probe[i]; i++) {
-                       if (!strcmp(apic_probe[i]->name, s+5)) { 
-                               changed = 1;
-                               genapic = apic_probe[i];
-                       }
-               }
-               if (!changed)
-                       printk(KERN_ERR "Unknown genapic `%s' specified.\n", s);
-               *p = old;
-       } 
        for (i = 0; !changed && apic_probe[i]; i++) { 
                if (apic_probe[i]->probe()) {
                        changed = 1;
                        genapic = apic_probe[i]; 
                } 
        }
-       /* Not visible without early console */ 
        if (!changed) 
-               panic("Didn't find an APIC driver"); 
+               genapic = &apic_default;
 
        printk(KERN_INFO "Using APIC driver %s\n", genapic->name);
 } 
diff -Nru a/xen/arch/x86/setup.c b/xen/arch/x86/setup.c
--- a/xen/arch/x86/setup.c      2005-05-30 18:02:07 -04:00
+++ b/xen/arch/x86/setup.c      2005-05-30 18:02:07 -04:00
@@ -21,7 +21,7 @@
 #include <asm/e820.h>
 
 extern void dmi_scan_machine(void);
-extern void generic_apic_probe(char *);
+extern void generic_apic_probe(void);
 
 /*
  * opt_xenheap_megabytes: Size of Xen heap in megabytes, excluding the
@@ -67,8 +67,6 @@
 extern int skip_ioapic_setup;
 boolean_param("noapic", skip_ioapic_setup);
 
-static char *xen_cmdline;
-
 int early_boot = 1;
 
 int ht_per_core = 1;
@@ -179,8 +177,7 @@
 
     dmi_scan_machine();
 
-    if ( xen_cmdline != NULL )
-        generic_apic_probe(xen_cmdline);
+    generic_apic_probe();
 
     acpi_boot_table_init();
     acpi_boot_init();
@@ -251,10 +248,7 @@
 

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