Date: Tue, 17 Feb 2009 23:58:26 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: xcllnt@mac.com Cc: mips@FreeBSD.org, tinderbox@FreeBSD.org, current@FreeBSD.org Subject: Re: [head tinderbox] failure on mips/mips Message-ID: <20090217.235826.-1697751865.imp@bsdimp.com> In-Reply-To: <B23797BE-91FB-4AE1-8370-E77D66ED05B6@mac.com> References: <4CB77F1D-4235-47D8-B654-1C4F29B6C649@mac.com> <20090217.234216.1276682135.imp@bsdimp.com> <B23797BE-91FB-4AE1-8370-E77D66ED05B6@mac.com>
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In message: <B23797BE-91FB-4AE1-8370-E77D66ED05B6@mac.com>
Marcel Moolenaar <xcllnt@mac.com> writes:
:
: On Feb 17, 2009, at 10:42 PM, M. Warner Losh wrote:
:
: > : A safer approach is to mark ifi_epoch as packed or put differently,
: > : define time_t as a 64-bit integral with 32-bit alignment. This can
: > : avoid a lot of unexpected internal padding as well (e.g. struct
: > : timeval).
: >
: > Marking it as packed won't help. If the elements aren't properly
: > aligned, gcc won't access multi-word entities properly. It might
: > eliminate the warning, but it will break at runtime.
:
: But GCC will use a pair of 32-bit loads and/or stores to
: access the 64-bit integral in that case. There should be
: no runtime breakage. You only do this for n32 of course.
Why only n32? Registers are still 64-bit in n32.
Warner
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