Workaround for GCC inline assembly bug, hopefully fixed for good. Builds for me in both checked and free
Bug details and status here: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=10153

Modified: trunk/reactos/hal/halx86/include/hal.h

--- trunk/reactos/hal/halx86/include/hal.h	2005-05-28 15:18:30 UTC (rev 15583)
+++ trunk/reactos/hal/halx86/include/hal.h	2005-05-28 15:41:09 UTC (rev 15584)
@@ -419,7 +419,7 @@

 static inline BYTE Ki386ReadFsByte(ULONG offset)
 {
    BYTE b;

-   __asm__ __volatile__("movb %%fs:(%1),%0":"=r" (b):"r" (offset));

+   __asm__ __volatile__("movb %%fs:(%1),%0":"=q" (b):"r" (offset));

    return b;
 }