From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 33658CAC5A7 for ; Wed, 24 Sep 2025 07:51:49 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1v1KHh-0003Vo-57; Wed, 24 Sep 2025 03:51:31 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v1KHf-0003VS-2S for qemu-devel@nongnu.org; Wed, 24 Sep 2025 03:51:27 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1v1KHW-00089a-MU for qemu-devel@nongnu.org; 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Wed, 24 Sep 2025 07:51:06 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.44]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9CB141955F19; Wed, 24 Sep 2025 07:51:03 +0000 (UTC) Date: Wed, 24 Sep 2025 08:50:59 +0100 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Paolo Bonzini Cc: Stefan Hajnoczi , qemu-devel@nongnu.org, Tanish Desai , Zhao Liu , Manos Pitsidianakis , Mads Ynddal Subject: Re: [PATCH 08/16] tracetool: Add Rust format support Message-ID: References: <20250919112536.141782-1-pbonzini@redhat.com> <20250919112536.141782-9-pbonzini@redhat.com> <20250923192354.GL509965@fedora> <85ebee67-3c30-4f14-93ca-d9cf65708619@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <85ebee67-3c30-4f14-93ca-d9cf65708619@redhat.com> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, DKIM_INVALID=0.1, DKIM_SIGNED=0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Sep 24, 2025 at 09:13:15AM +0200, Paolo Bonzini wrote: > On 9/23/25 21:23, Stefan Hajnoczi wrote: > > > + out('// SPDX-License-Identifier: GPL-2.0-or-later', > > > + '// This file is @generated by tracetool, do not edit.', > > > + '', > > > + '#[allow(unused_imports)]', > > > + 'use std::ffi::c_char;', > > > + '#[allow(unused_imports)]', > > > + 'use util::bindings;', > > > + '', > > > + '#[inline(always)]', > > > + 'fn trace_event_get_state_dynamic_by_id(_id: u16) -> bool {', > > > + ' unsafe { (trace_events_enabled_count != 0) && (_id != 0) }', > > > + '}', > > > > This was translated to Rust from: > > > > /* it's on fast path, avoid consistency checks (asserts) */ > > #define trace_event_get_state_dynamic_by_id(id) \ > > (unlikely(trace_events_enabled_count) && _ ## id ## _DSTATE) > > > > The _id != 0 expression is incorrect. The purpose was to check whether > > the trace event is currently enabled (i.e. dynamically at runtime). > > The expression is correct, but the function and argument names are not. It > should be > > fn trace_event_state_is_enabled(dstate: u16) -> bool { > unsafe { trace_events_enabled_count } != 0 && dstate != 0 > } > > > > + # static state > > > + for e in events: > > > + if 'disable' in e.properties: > > > + enabled = "false" > > > + else: > > > + enabled = "true" > > > > What is the purpose of this loop? The variable enabled is unused so I > > think it can be deleted. > > The Rust code generator is not emitting any code for disabled tracepoints. > Unlike C, where the disabled tracepoints can produce e.g. -Wformat warnings, > there's no real benefit here. > > In the RFC the "enabled" variable was used to produce a const for the static > state; it had no user so I removed it, but I left behind this dead Python > code. Sorry about that! Is the concept of build time 'disabled' tracepoints actually useful to still support ? AFAICT we use it in only places, which doesn't make it sound too compelling: $ find -name trace-events | xargs grep '^disable' ./target/hppa/trace-events:disable hppa_tlb_flush_ent(void *env, void *ent, uint64_t va_b, uint64_t va_e, uint64_t pa) "env=%p ent=%p va_b=0x%lx va_e=0x%lx pa=0x%lx" ./target/hppa/trace-events:disable hppa_tlb_find_entry(void *env, void *ent, int valid, uint64_t va_b, uint64_t va_e, uint64_t pa) "env=%p ent=%p valid=%d va_b=0x%lx va_e=0x%lx pa=0x%lx" ./target/hppa/trace-events:disable hppa_tlb_find_entry_not_found(void *env, uint64_t addr) "env=%p addr=%08lx" ...snip... ./target/hppa/trace-events:disable hppa_tlb_lpa_success(void *env, uint64_t addr, uint64_t phys) "env=%p addr=0x%lx phys=0x%lx" ./target/hppa/trace-events:disable hppa_tlb_lpa_failed(void *env, uint64_t addr) "env=%p addr=0x%lx" ./target/hppa/trace-events:disable hppa_tlb_probe(uint64_t addr, int level, int want) "addr=0x%lx level=%d want=%d" ./hw/display/trace-events:disable qxl_io_write_vga(int qid, const char *mode, uint32_t addr, uint32_t val) "%d %s addr=%u val=%u" With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|