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References: <1465023763-10773-1-git-send-email-dmitry@daynix.com>
From: Jason Wang <jasowang@redhat.com>
Message-ID: <5754CF7E.4050908@redhat.com>
Date: Mon, 6 Jun 2016 09:18:54 +0800
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Subject: Re: [Qemu-devel] [PATCH] e1000e: Fix build with gcc 4.6.3 and ust
 tracing
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To: Dmitry Fleytman <dmitry@daynix.com>, qemu-devel@nongnu.org
Cc: Yan Vugenfirer <yan@daynix.com>, Peter Maydell <peter.maydell@linaro.org>, Leonid Bloch <leonid@daynix.com>, Shmulik Ladkani <shmulik.ladkani@ravellosystems.com>



On 2016=E5=B9=B406=E6=9C=8804=E6=97=A5 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 =E2=80=98e1000e_io_write=E2=80=99:
> hw/net/e1000e.c:170:39: error: =E2=80=98idx=E2=80=99 may be used uninit=
ialized in this function [-Werror=3Duninitialized]
> hw/net/e1000e.c: In function =E2=80=98e1000e_io_read=E2=80=99:
> hw/net/e1000e.c:145:35: error: =E2=80=98idx=E2=80=99 may be used uninit=
ialized in this function [-Werror=3Duninitialized]
> 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 =3D opaque;
> -    uint32_t idx;
> +    uint32_t idx =3D 0;
>       uint64_t val;
>  =20
>       switch (addr) {
> @@ -158,7 +158,7 @@ e1000e_io_write(void *opaque, hwaddr addr,
>                   uint64_t val, unsigned size)
>   {
>       E1000EState *s =3D opaque;
> -    uint32_t idx;
> +    uint32_t idx =3D 0;
>  =20
>       switch (addr) {
>       case E1000_IOADDR:

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

Maybe in the future, we need something like uninitialized_var() tricks=20
in Linux for this.