Marcelo Tosatti wrote:
Some pvmmu functions store their commands on stack, and newer GCC versions conclude that these commands are unused.So stick an inline asm statement to convince the compiler otherwise. Signed-off-by: Marcelo Tosatti <[EMAIL PROTECTED]> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c index 8b7a3cf..c892752 100644 --- a/arch/x86/kernel/kvm.c +++ b/arch/x86/kernel/kvm.c @@ -55,6 +55,12 @@ static void kvm_mmu_op(void *buffer, unsigned len) int r; unsigned long a1, a2;+ /*+ * GCC 4.3.0 concludes that on-stack kvm_mmu_op* is unused and + * optimizes its initialization away. + */ + asm ("" : : "p" (buffer)); +
I don't think "p" should force the contents into memory? Perhaps "m"(*(char *)buffer)?
Anthony, I don't see why a memory clobber would tell gcc that the variables is actually used. The problem is with the void * -> unsigned long cast (__pa), once that happens gcc loses track. It's probably needed anyway since hypercalls _do_ clobber memory.
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