XXX nobios

*** 139,150 ****
--- 139,152 ----
  int force_fastreboot = 0;
  volatile int fastreboot_onpanic = 0;
  int post_fastreboot = 0;
  #ifdef  __xpv
  volatile int fastreboot_capable = 0;
+ boolean_t bios_calls_available = B_FALSE;
  #else
  volatile int fastreboot_capable = 1;
+ boolean_t bios_calls_available = B_TRUE;
  #endif
  
  /*
   * Information saved from current boot for fast reboot.
   * If the information size exceeds what we have allocated, fast reboot
*** 2507,2516 ****
--- 2509,2560 ----
          plat_dr_options |= PLAT_DR_FEATURE_MEMORY;
  
          return (tp);
  }
  
+ /*
+  * If this system has a PC-compatible BIOS, it will have handlers for
+  * various well-known BIOS calls.  These calls take the form of INT
+  * instructions, revectoring to the nominated entry in the real mode
+  * Interrupt Vector Table (IVT).  If all of the commonly used entries (from
+  * INT 10h up to INT 1Ah) are zero, we almost certainly don't want to make
+  * use of BOP_DOINT() later.
+  *
+  * The IVT begins at linear address 0 on the 8086.  Though later CPUs
+  * allowed it to be moved, it seems that most BIOS implementations choose
+  * not to do so for compatibility reasons.  Our BIOS call trampoline (see
+  * "idt_info" in "uts/i86pc/ml/bios_call_src.s") also assumes this address.
+  */
+ static int
+ system_has_bios(void)
+ {
+         uint32_t all_ivts = 0;
+ 
+         DBG_MSG("\nBIOS IVT Entries:\n");
+         for (uint32_t intnum = 0x10; intnum <= 0x1a; intnum++) {
+                 /*
+                  * The first software interrupt number (i.e. INT 0h) maps to
+                  * vector number 32 in the IVT.  Each entry in the IVT is
+                  * four bytes, describing a 16 bit far call address.
+                  */
+                 uintptr_t slot = 4 * (32 + intnum);
+                 uint32_t ivte = *((uint32_t *)slot);
+ 
+                 if (ivte != 0) {
+                         DBG(intnum);
+                         DBG(ivte);
+                 }
+                 all_ivts |= ivte;
+         }
+         if (all_ivts == 0) {
+                 DBG_MSG("System has no BIOS IVT entries\n");
+         }
+         DBG_MSG("\n");
+ 
+         return (all_ivts != 0);
+ }
+ 
  #else /* __xpv */
  static void
  enumerate_xen_cpus()
  {
          processorid_t   id, max_id;
*** 2540,2549 ****
--- 2584,2596 ----
  build_firmware_properties(void)
  {
          ACPI_TABLE_HEADER *tp = NULL;
  
  #ifndef __xpv
+         if (do_bsys_getproplen(NULL, "no-bios") > 0 || !system_has_bios())
+                 bios_calls_available = B_FALSE;
+ 
          if ((tp = find_fw_table(ACPI_SIG_MSCT)) != NULL)
                  msct_ptr = process_msct((ACPI_TABLE_MSCT *)tp);
          else
                  msct_ptr = NULL;