Re: [Qemu-devel] [PATCH] e1000e: Fix build with gcc 4.6.3 and ust tracing

[Jason Wang <jasowang@redhat.com>]

On 2016年06月04日 15:02, Dmitry Fleytman wrote:
> This patch fixes used-uninitialized false
> positive while compiling with ust tracing
> backend plus gcc 4.6.3:
>
> hw/net/e1000e.c: In function ‘e1000e_io_write’:
> hw/net/e1000e.c:170:39: error: ‘idx’ may be used uninitialized in this function [-Werror=uninitialized]
> hw/net/e1000e.c: In function ‘e1000e_io_read’:
> hw/net/e1000e.c:145:35: error: ‘idx’ may be used uninitialized in this function [-Werror=uninitialized]
> cc1: all warnings being treated as errors
> make: *** [hw/net/e1000e.o] Error 1
>
> Signed-off-by: Dmitry Fleytman <dmitry@daynix.com>
> ---
>   hw/net/e1000e.c | 4 ++--
>   1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/hw/net/e1000e.c b/hw/net/e1000e.c
> index 61bcbb6..692283f 100644
> --- a/hw/net/e1000e.c
> +++ b/hw/net/e1000e.c
> @@ -133,7 +133,7 @@ static uint64_t
>   e1000e_io_read(void *opaque, hwaddr addr, unsigned size)
>   {
>       E1000EState *s = opaque;
> -    uint32_t idx;
> +    uint32_t idx = 0;
>       uint64_t val;
>   
>       switch (addr) {
> @@ -158,7 +158,7 @@ e1000e_io_write(void *opaque, hwaddr addr,
>                   uint64_t val, unsigned size)
>   {
>       E1000EState *s = opaque;
> -    uint32_t idx;
> +    uint32_t idx = 0;
>   
>       switch (addr) {
>       case E1000_IOADDR:

Acked-by: Jason Wang <jasowang@redhat.com>

Maybe in the future, we need something like uninitialized_var() tricks 
in Linux for this.