From: Gordon Malm <gengor@gentoo.org>

Make inline asm PIC-safe (do not clobber ebx).

Credit to Anthony Basile for fixes on x86-64.

Reference: http://bugs.gentoo.org/200376

--- a/checkvm/checkvm.c
+++ b/checkvm/checkvm.c
@@ -79,8 +79,18 @@ getVersion(uint32 *version)
 {
    uint32 eax, ebx, ecx, edx;
    
-   __asm__ volatile("inl (%%dx)" :
-   	            "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :
+#ifdef __x86_64__
+   __asm__ volatile("pushq %%rbx      \n\t"
+		    "inl (%%dx)       \n\t"
+		    "movl %%ebx, %3   \n\t"
+		    "popq %%rbx       \n\t" :
+#else
+   __asm__ volatile("pushl %%ebx      \n\t"
+		    "inl (%%dx)       \n\t"
+		    "movl %%ebx, %3   \n\t"
+		    "popl %%ebx       \n\t" :
+#endif
+		    "=a"(eax), "=c"(ecx), "=d"(edx), "=r"(ebx) :
 		    "0"(BDOOR_MAGIC), "1"(BDOOR_CMD_GETVERSION),
 		    "2"(BDOOR_PORT) : "memory");
    version[0] = eax;
@@ -97,7 +107,7 @@ getHWVersion(uint32 *hwVersion)
    uint32 eax, ebx, ecx, edx;
    
    __asm__ volatile("inl (%%dx)" :
-   	            "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :
+		    "=a"(eax), "=c"(ecx), "=d"(edx), "=r"(ebx) :
 		    "0"(BDOOR_MAGIC), "1"(BDOOR_CMD_GETHWVERSION),
 		    "2"(BDOOR_PORT) : "memory");
    *hwVersion = eax;
@@ -113,7 +123,7 @@ getScreenSize(uint32 *screensize)
    uint32 eax, ebx, ecx, edx;
    
    __asm__ volatile("inl (%%dx)" :
-   		    "=a"(eax), "=c"(ecx), "=d"(edx), "=b"(ebx) :
+		    "=a"(eax), "=c"(ecx), "=d"(edx), "=r"(ebx) :
 		    "0"(BDOOR_MAGIC), "1"(BDOOR_CMD_GETSCREENSIZE),
 		    "2"(BDOOR_PORT) : "memory");
    *screensize = eax;