Date: Tue, 15 Aug 2006 09:13:51 -0400 From: John Baldwin <jhb@freebsd.org> To: David Xu <davidxu@freebsd.org> Cc: cvs-src@freebsd.org, src-committers@freebsd.org, cvs-all@freebsd.org Subject: Re: cvs commit: src/sys/amd64/amd64 support.S Message-ID: <200608150913.52419.jhb@freebsd.org> In-Reply-To: <200608151245.k7FCjpJo077372@repoman.freebsd.org> References: <200608151245.k7FCjpJo077372@repoman.freebsd.org>
next in thread | previous in thread | raw e-mail | index | archive | help
On Tuesday 15 August 2006 08:45, David Xu wrote: > davidxu 2006-08-15 12:45:51 UTC > > FreeBSD src repository > > Modified files: > sys/amd64/amd64 support.S > Log: > Because fuword on AMD64 returns 64bit long integer -1 on fault, clear > entire %rax to zero instead of only clearing %eax, otherwise it will > leave garbage data in upper 32 bits. Are you sure that 'xorl %eax,%eax' doesn't actually clear all 64 bits? This practice of just using xorl rather than xorq is all over the place in the amd64 code, and I think I've even seen gcc generate it, so I'm guessing that the xorl actually is a xorq. -- John Baldwin
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?200608150913.52419.jhb>