> On 8 Mar 2017, at 22:16, Victor Toso <li...@victortoso.com> wrote: > > Hi, > > On Wed, Mar 08, 2017 at 07:21:15PM +0100, Christophe de Dinechin wrote: >> I have several errors like this: >> >> spice-channel.c:1923:12: error: cast from 'uint8_t *' (aka 'unsigned char >> *') to >> 'uint32_t *' (aka 'unsigned int *') increases required alignment from 1 >> to >> 4 [-Werror,-Wcast-align] >> ...(uint32_t *)((uint8_t *)c->peer_msg + >> GUINT32_FROM_LE(c->peer_msg->caps_offset)); >> >> ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ >> >> Is there any guarantee that the result pointer will be 32-bit aligned? >> In other words, is it guaranteed that the c->peer_msg->caps_offset >> will be a multiple of 4? I don’t see this written in the spec. >> >> Based on the answer, the correct fix is: >> >> - If aligned, to cast to a uint32_t * in a way that disables the warning >> >> - If misaligned, to replaced *p with a read operation that is safe when >> mis-aligned (OS dependent I guess) > > Yes, we should check case-by-case. I started doing some work around this > (nearly one and half year ago already!) but I got stuck on explaining > the rationale for each cast which would avoid the warnings. > > You can see the comments and suggestions at the time are in the > following thread: > > https://lists.freedesktop.org/archives/spice-devel/2015-August/021535.html > <https://lists.freedesktop.org/archives/spice-devel/2015-August/021535.html>
Ach, I see you used SPICE_ALIGNED_CAST and SPICE_UNALIGNED_CAST. I used SPICE_REALIGN_CAST :-( Will try to integrate your patches, thanks. > > Cheers, > toso >> >> >> Thanks >> Christophe >> >> _______________________________________________ >> Spice-devel mailing list >> Spice-devel@lists.freedesktop.org <mailto:Spice-devel@lists.freedesktop.org> >> https://lists.freedesktop.org/mailman/listinfo/spice-devel >> <https://lists.freedesktop.org/mailman/listinfo/spice-devel>
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