Re: [PATCH] tools/kdd: silence gcc 8 warning a different way

From: Tim Deegan <tim@xen.org>
To: Wei Liu <wei.liu2@citrix.com>
Cc: Juergen Gross <jgross@suse.com>,
	xen-devel <xen-devel@lists.xenproject.org>,
	Ian Jackson <Ian.Jackson@eu.citrix.com>,
	Marek Marczykowski <marmarek@invisiblethingslab.com>,
	Jan Beulich <JBeulich@suse.com>
Subject: Re: [PATCH] tools/kdd: silence gcc 8 warning a different way
Date: Mon, 16 Apr 2018 16:20:44 +0100	[thread overview]
Message-ID: <20180416152044.GA84326@deinos.phlegethon.org> (raw)
In-Reply-To: <20180416082948.g6yhqwilqlorfciw@citrix.com>

At 09:29 +0100 on 16 Apr (1523870989), Wei Liu wrote:
> Cc Tim
> On Thu, Apr 12, 2018 at 06:04:49AM -0600, Jan Beulich wrote:
> > Older gcc doesn't like "#pragma GCC diagnostic" inside functions.
> > 
> > Signed-off-by: Jan Beulich <jbeulich@suse.com>
> > 
> > --- a/tools/debugger/kdd/kdd.c
> > +++ b/tools/debugger/kdd/kdd.c
> > @@ -695,10 +695,10 @@ static void kdd_handle_read_ctrl(kdd_sta
> >              KDD_LOG(s, "Request outside of known control space\n");
> >              len = 0;
> >          } else {
> > -#pragma GCC diagnostic push
> > -#pragma GCC diagnostic ignored "-Warray-bounds"
> > -            memcpy(buf, ((uint8_t *)&ctrl.c32) + offset, len);
> > -#pragma GCC diagnostic pop
> > +            /* Suppress bogus gcc 8 "out of bounds" warning. */
> > +            const uint8_t *src;
> > +            asm ("" : "=g" (src) : "0" ((uint8_t *)&ctrl.c32 + offset));

That's terrifying!  Does casting the offset to uint32_t not DTRT?

Tim.

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