From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: [PATCH v5] eal_common_cpuflags: Fix %rbx corruption, and simplify the code Date: Tue, 25 Mar 2014 13:51:04 -0700 Message-ID: <5331EC38.2070901@linux.intel.com> References: <20140320163921.GC7721@hmsreliant.think-freely.org> <1395777179-4345-1-git-send-email-nhorman@tuxdriver.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit To: Neil Horman , dev-VfR2kkLFssw@public.gmane.org Return-path: In-Reply-To: <1395777179-4345-1-git-send-email-nhorman-2XuSBdqkA4R54TAoqtyWWQ@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" On 03/25/2014 12:52 PM, Neil Horman wrote: > Neil Horman reported that on x86-64 the upper half of %rbx would get > clobbered when the code was compiled PIC or PIE, because the > i386-specific code to preserve %ebx was incorrectly compiled. > > However, the code is really way more complex than it needs to be. For > one thing, the CPUID instruction only needs %eax (leaf) and %ecx > (subleaf) as parameters, and since we are testing for bits, we might > as well list the bits explicitly. Furthermore, we can use an array > rather than doing a switch statement inside a structure. > > Reported-by: Neil Horman > Signed-off-by: H. Peter Anvin > Signed-off-by: Neil Horman > Looks good to me. Reviewed-by: H. Peter Anvin -hpa