Merge pull request #89 from w-woloszyn/freeze

Fix build with X2APIC false
jovanbulck · Sep 30, 2024 · 811395c · 811395c
2 parents 1483dc8 + 5045bf9
commit 811395c
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diff --git a/README.md b/README.md
@@ -129,7 +129,7 @@ below.
 
 | Linux kernel parameter               | Motivation                                                                                                                                                                     |
 | ------------------------------------ | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
-| `nox2apic`                           | Optionally configure local APIC device in memory-mapped I/O mode (to make use of SGX-Step's precise single-stepping features). Alternatively, you can leave the CPU in x2APIC mode and recent SGX-Step distributions should also be compatible.                                                            |
+| `nox2apic`                           | Optionally configure local APIC device in memory-mapped I/O mode (to make use of SGX-Step's precise single-stepping features). If set, make sure to set X2APIC to 0 in libsgxstep/config.h. Alternatively, you can leave the CPU in x2APIC mode and recent SGX-Step distributions should also be compatible.                                                            |
 | `iomem=relaxed no_timer_check`       | Suppress unneeded warning messages in the kernel logs.                                                                                                                         |
 | `nmi_watchdog=0`                     | Suppress the kernel NMI watchdog.                                                                                                                                              |
 | `isolcpus=1`                         | Affinitize the victim process to an isolated CPU core.                                                                                                                         |

diff --git a/libsgxstep/apic.h b/libsgxstep/apic.h
@@ -74,6 +74,7 @@ void apic_init(void);
 
 /* read/write functions for XAPIC in MMIO access mode */
 #if !X2APIC
+extern void* apic_base;
     /*
      * From Linux kernel source: /arch/x86/include/asm/apic.h
      * NOTE: Intel SDM: "any access that touches bytes 4 through 15 of an APIC