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CTRY:IE; LANG:en; SCL:1; SRV:; IPV:CAL; SFV:NSPM; H:64aa7808-outbound-1.mta.getcheckrecipient.com; PTR:ec2-63-35-35-123.eu-west-1.compute.amazonaws.com; CAT:NONE; SFS:(13230040)(82310400026)(1800799024)(36860700013)(376014)(35042699022); DIR:OUT; SFP:1101; X-OriginatorOrg: arm.com X-MS-Exchange-CrossTenant-OriginalArrivalTime: 07 Oct 2024 17:30:33.7916 (UTC) X-MS-Exchange-CrossTenant-Network-Message-Id: 9a048ab4-8b07-477d-72c3-08dce6f5bfbe X-MS-Exchange-CrossTenant-Id: f34e5979-57d9-4aaa-ad4d-b122a662184d X-MS-Exchange-CrossTenant-OriginalAttributedTenantConnectingIp: TenantId=f34e5979-57d9-4aaa-ad4d-b122a662184d; Ip=[63.35.35.123]; Helo=[64aa7808-outbound-1.mta.getcheckrecipient.com] X-MS-Exchange-CrossTenant-AuthSource: DB5PEPF00014B89.eurprd02.prod.outlook.com X-MS-Exchange-CrossTenant-AuthAs: Anonymous X-MS-Exchange-CrossTenant-FromEntityHeader: HybridOnPrem X-MS-Exchange-Transport-CrossTenantHeadersStamped: AM8PR08MB6323 X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org > > Hi Bruce, > > Why x86/rte_cpuflags.c is not using rte_getauxval() ? >=20 > I don't see any such DPDK function, unless I'm missing something? I do se= e a > linux function which includes hw capability flags. I suspect the reasons = we > don't use that are: >=20 > 1. Lack of awareness of it (at least on my end! :-)) 2. Originally when w= e added > flags for new instruction sets we may have > needed to support their detection on platforms where the kernel/libc w= as > too old to be aware of them. > 3. It's linux only, so we'd still need these cpuid calls for other OS's > anyway. >=20 > Therefore, I don't see any benefit in using that function over what we do= now. > Is there some benefit that you see that makes you think it would be > worthwhile switching? >=20 Agree, all these are good reasons to avoid it.=20 getauxval() reads these values from process stack (ELF loader places it the= re), so it's a relatively fast way of finding cpu features. I'm wondering if a similar m= echanism is available in FreeBSD and Windows.=20 If so, it might be beneficial to have a common API for such functions. But as you mentioned, if the kernel isn't aware of the feature it may fail.= =20