Hi, I have following snippet of code. Code A __asm__ __volatile__( " lock ;\n" " addl %1,%0 ;\n" : "=m" (my_var) : "ir" (my_int), "m" (my_var) : /* no clobber-list */ ); Code B __asm__ __volatile__( "decl %0; sete %1" : "=m" (my_var), "=q" (cond) : "m" (my_var) : "memory" ); In Code A memory contents are getting updated. And in Code B memory contents and 'cond' var are getting updated. In Code B in cobbler column 'memory' is used to indicate that this code modifies memory contents. But where as in Code A it was not mentioned Is is not that Code A is wrong, for not mentioning cobbler list 'memory' to indicate memory contents are getting updated. Please rectify me, if I am wrong. Also, what does '+m' constraint mean, if I use in inline assembly. -- Regards, Sri.