--- src/kernel/sel4/libsel4/sel4_arch_include/ia32/sel4/sel4_arch/syscalls.h
+++ src/kernel/sel4/libsel4/sel4_arch_include/ia32/sel4/sel4_arch/syscalls.h
@@ -20,19 +20,21 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%ecx, %%ebp \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
-        :
+        : "+d" (dest)
         : "a" (seL4_SysSend),
-        "b" (dest),
         "S" (msgInfo.words[0]),
         "D" (seL4_GetMR(0)),
         "c" (seL4_GetMR(1))
-        : "%edx"
+        :
     );
 }
 
@@ -42,19 +44,21 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%ecx, %%ebp \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
-        :
+        : "+d" (dest)
         : "a" (seL4_SysSend),
-        "b" (dest),
         "S" (msgInfo.words[0]),
         "D" (mr0 != seL4_Null ? *mr0 : 0),
         "c" (mr1 != seL4_Null ? *mr1 : 0)
-        : "%edx"
+        :
     );
 }
 
@@ -63,19 +67,21 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%ecx, %%ebp \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
-        :
+        : "+d" (dest)
         : "a" (seL4_SysNBSend),
-        "b" (dest),
         "S" (msgInfo.words[0]),
         "D" (seL4_GetMR(0)),
         "c" (seL4_GetMR(1))
-        : "%edx"
+        :
     );
 }
 
@@ -85,19 +91,21 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%ecx, %%ebp \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
-        :
+        : "+d" (dest)
         : "a" (seL4_SysNBSend),
-        "b" (dest),
         "S" (msgInfo.words[0]),
         "D" (mr0 != seL4_Null ? *mr0 : 0),
         "c" (mr1 != seL4_Null ? *mr1 : 0)
-        : "%edx"
+        :
     );
 }
 
@@ -106,18 +114,20 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%ecx, %%ebp \n"
         "movl %%esp, %%ecx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
         :
         : "a" (seL4_SysReply),
         "S" (msgInfo.words[0]),
         "D" (seL4_GetMR(0)),
         "c" (seL4_GetMR(1))
-        : "%ebx", "%edx"
+        : "%edx"
     );
 }
 
@@ -127,18 +137,20 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%ecx, %%ebp \n"
         "movl %%esp, %%ecx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
         :
         : "a" (seL4_SysReply),
         "S" (msgInfo.words[0]),
         "D" (mr0 != seL4_Null ? *mr0 : 0),
         "c" (mr1 != seL4_Null ? *mr1 : 0)
-        : "%ebx", "%edx"
+        : "%edx"
     );
 }
 
@@ -147,16 +159,18 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
-        :
+        : "+d" (dest)
         : "a" (seL4_SysSend),
-        "b" (dest),
         "S" (seL4_MessageInfo_new(0, 0, 0, 0).words[0])
-        : "%ecx", "%edx"
+        : "%ecx"
     );
 }
 
@@ -170,20 +184,24 @@
 
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "movl %%ebx, %%edx \n"
+        "popl %%ebx        \n"
         "movl %%ebp, %%ecx \n"
         "popl %%ebp        \n"
         :
-        "=b" (badge),
+        "=d" (badge),
         "=S" (info.words[0]),
         "=D" (mr0),
         "=c" (mr1)
         : "a" (seL4_SysRecv),
-        "b" (src)
-        : "%edx", "memory"
+        "d" (src)
+        : "memory"
     );
 
     seL4_SetMR(0, mr0);
@@ -207,20 +225,24 @@
 
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "movl %%ebx, %%edx \n"
+        "popl %%ebx        \n"
         "movl %%ebp, %%ecx \n"
         "popl %%ebp        \n"
         :
-        "=b" (badge),
+        "=d" (badge),
         "=S" (info.words[0]),
         "=D" (msg0),
         "=c" (msg1)
         : "a" (seL4_SysRecv),
-        "b" (src)
-        : "%edx", "memory"
+        "d" (src)
+        : "memory"
     );
 
     if (mr0 != seL4_Null) {
@@ -247,20 +269,23 @@
 
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%esp, %%ecx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "movl %%ebx, %%edx \n"
+        "popl %%ebx        \n"
         "movl %%ebp, %%ecx \n"
         "popl %%ebp        \n"
         :
-        "=b" (badge),
+        "=d" (badge),
         "=S" (info.words[0]),
         "=D" (mr0),
         "=c" (mr1)
         : "a" (seL4_SysNBRecv),
-        "b" (src)
-        : "%edx", "memory"
+        "d" (src)
+        : "memory"
     );
 
     seL4_SetMR(0, mr0);
@@ -282,24 +307,27 @@
 
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%ecx, %%ebp \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "movl %%ebx, %%edx \n"
+        "popl %%ebx        \n"
         "movl %%ebp, %%ecx \n"
         "popl %%ebp        \n"
         :
         "=S" (info.words[0]),
         "=D" (mr0),
         "=c" (mr1),
-        "=b" (dest) /* dummy, tells GCC that ebx is clobbered */
+        "+d" (dest)
         : "a" (seL4_SysCall),
-        "b" (dest),
         "S" (msgInfo.words[0]),
         "D" (mr0),
         "c" (mr1)
-        : "%edx", "memory"
+        : "memory"
     );
 
     seL4_SetMR(0, mr0);
@@ -325,24 +353,27 @@
 
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%ecx, %%ebp \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "movl %%ebx, %%edx \n"
+        "popl %%ebx        \n"
         "movl %%ebp, %%ecx \n"
         "popl %%ebp        \n"
         :
         "=S" (info.words[0]),
         "=D" (msg0),
         "=c" (msg1),
-        "=b" (dest) /* dummy, tells GCC that ebx is clobbered */
+        "+d" (dest)
         : "a" (seL4_SysCall),
-        "b" (dest),
         "S" (msgInfo.words[0]),
         "D" (msg0),
         "c" (msg1)
-        : "%edx", "memory"
+        : "memory"
     );
 
     if (mr0 != seL4_Null) {
@@ -365,24 +396,28 @@
 
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%ecx, %%ebp \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "movl %%ebx, %%edx \n"
+        "popl %%ebx        \n"
         "movl %%ebp, %%ecx \n"
         "popl %%ebp        \n"
         :
-        "=b" (badge),
+        "=d" (badge),
         "=S" (info.words[0]),
         "=D" (mr0),
         "=c" (mr1)
         : "a" (seL4_SysReplyRecv),
-        "b" (dest),
+        "d" (dest),
         "S" (msgInfo.words[0]),
         "D" (mr0),
         "c" (mr1)
-        : "%edx", "memory"
+        : "memory"
     );
 
     seL4_SetMR(0, mr0);
@@ -413,24 +448,27 @@
 
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%ecx, %%ebp \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "movl %%ebx, %%edx \n"
+        "popl %%ebx        \n"
         "movl %%ebp, %%ecx \n"
         "popl %%ebp        \n"
         :
-        "=b" (badge),
+        "+d" (badge),
         "=S" (info.words[0]),
         "=D" (msg0),
         "=c" (msg1)
         : "a" (seL4_SysReplyRecv),
-        "b" (dest),
         "S" (msgInfo.words[0]),
         "D" (msg0),
         "c" (msg1)
-        : "%edx", "memory"
+        : "memory"
     );
 
     if (mr0 != seL4_Null) {
@@ -452,14 +490,16 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%esp, %%ecx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
         :
         : "a" (seL4_SysYield)
-        : "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory"
+        : "%ecx", "%edx", "%esi", "%edi", "memory"
     );
 }
 
@@ -469,15 +509,17 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
-        :
-        : "a" (seL4_SysDebugPutChar),
-        "b" (c)
-        : "%ecx", "%edx", "%esi", "%edi", "memory"
+        : "+d" (c)
+        : "a" (seL4_SysDebugPutChar)
+        : "%ecx", "%esi", "%edi", "memory"
     );
 }
 #endif
@@ -488,14 +530,16 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%esp, %%ecx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
         :
         : "a" (seL4_SysDebugHalt)
-        : "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory"
+        : "%ecx", "%edx", "%esi", "%edi", "memory"
     );
 }
 #endif
@@ -506,14 +550,16 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%esp, %%ecx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
         :
         : "a" (seL4_SysDebugSnapshot)
-        : "%ebx", "%ecx", "%edx", "%esi", "%edi", "memory"
+        : "%ecx", "%edx", "%esi", "%edi", "memory"
     );
 }
 #endif
@@ -524,14 +570,18 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "movl %%ebx, %%edx \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
-        : "=b"(cap)
-        : "a"(seL4_SysDebugCapIdentify), "b"(cap)
-        : "%ecx", "%edx", "%esi", "%edi", "memory"
+        : "+d"(cap)
+        : "a"(seL4_SysDebugCapIdentify)
+        : "%ecx", "%esi", "%edi", "memory"
     );
     return (seL4_Uint32)cap;
 }
@@ -546,14 +596,17 @@
 
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
-        :
-        : "a"(seL4_SysDebugNameThread), "b"(tcb)
-        : "%ecx", "%edx", "%esi", "%edi", "memory"
+        : "+d" (tcb)
+        : "a"(seL4_SysDebugNameThread)
+        : "%ecx", "%esi", "%edi", "memory"
     );
 }
 #endif
@@ -564,16 +617,18 @@
 {
     asm volatile (
         "pushl %%ebp       \n"
+        "pushl %%ebx       \n"
         "movl %%esp, %%ecx \n"
+        "movl %%edx, %%ebx \n"
         "leal 1f, %%edx    \n"
         "1:                \n"
         "sysenter          \n"
+        "popl %%ebx        \n"
         "popl %%ebp        \n"
-        :
+        : "+d" (userfn)
         : "a" (seL4_SysDebugRun),
-        "b" (userfn),
         "S" (userarg)
-        : "%ecx", "%edx", "%edi", "memory"
+        : "%ecx", "%edi", "memory"
     );
 }
 #endif
@@ -600,16 +655,19 @@
 {
     asm volatile (
         "pushl %%ebp        \n"
+        "pushl %%ebx        \n"
         "movl %%esp, %%ecx  \n"
+        "movl %%edx, %%ebx  \n"
         "leal 1f, %%edx     \n"
         "1:                 \n"
         "sysenter           \n"
+        "movl %%ebx, %%edx  \n"
+        "popl %%ebx         \n"
         "popl %%ebp         \n"
-        : "=b" (start)
+        : "+d" (start)
         : "a" (seL4_SysBenchmarkDumpLog),
-        "b" (start),
         "S" (size)
-        : "%ecx", "%edx", "%edi", "memory"
+        : "%ecx", "%edi", "memory"
     );
 
     return (seL4_Uint32) start;
@@ -622,14 +680,17 @@
     seL4_Uint32 ret = 0;
     asm volatile (
         "pushl %%ebp        \n"
+        "pushl %%ebx        \n"
         "movl %%esp, %%ecx  \n"
         "leal 1f, %%edx     \n"
         "1:                 \n"
         "sysenter           \n"
+        "movl %%ebx, %%edx  \n"
+        "popl %%ebx         \n"
         "popl %%ebp         \n"
-        : "=b" (ret)
+        : "=d" (ret)
         : "a" (seL4_SysBenchmarkLogSize)
-        : "%ecx", "%edx", "%edi", "memory"
+        : "%ecx", "%edi", "memory"
     );
 
     return ret;