From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 7FFCE22A80D for ; Sat, 5 Sep 2026 05:17:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788585443; cv=none; b=Awavh5VIrw8V1rWcMvFvsktanl9PYTcL/SDuHktET/bg3CyJhQk3/hrpoxCciTWzfDO/kZ2mcAQpb53ywYC/22zsKMxHQPKju/NeMBws4sUxQDuv9UWyLGHNqTGSoyhEORMqVvmbBwl5NZ8moLZSqKgwsRxaAuBql/9XAzmAK8g= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788585443; c=relaxed/simple; bh=xCw3BKMnnnpcM6cHV4oiS+dkkkFjk9pf8nZpwMCYcTY=; h=Date:From:To:CC:Subject:In-Reply-To:References:Message-ID: MIME-Version:Content-Type; b=Df2qXyMq9bBI9zRAxDTbLwysKcqyfaVsADLPuAUOyhyCw1HoeyhImJcHHoJQdz+fPojItduUq1PsiEdj/3matwi6etJ/ubc8bu89MpmEe+fpIIHJojJH1cS68IEAVbrt4ZzZORqLrBVUnzmpCwhy8Xv/XmBqxsTWH5gS9K2huo4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=JpGqlvLZ; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="JpGqlvLZ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1788585440; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xCw3BKMnnnpcM6cHV4oiS+dkkkFjk9pf8nZpwMCYcTY=; b=JpGqlvLZUehpZcnwEOkGECjjGLh+wpzw5Tzrn2XIzXKG7jCbMCOfXytXBNdHddtUrAzV+x LFA7BdPJD8qWLocmNZFo2wJ3PSvBG3UB7BUcENvcu/Wcttdn6Dc9cPJBnw+O59+FXjrQ6T NeJbuyo3ulvJFFVn3Vga2on3KULyP2U= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-138-rsYegfaPPEWoSrTH-_NW0g-1; Sat, 05 Sep 2026 01:17:16 -0400 X-MC-Unique: rsYegfaPPEWoSrTH-_NW0g-1 X-Mimecast-MFC-AGG-ID: rsYegfaPPEWoSrTH-_NW0g_1788585436 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-49545071724so12350915e9.0 for ; Fri, 04 Sep 2026 22:17:16 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788585435; x=1789190235; h=content-transfer-encoding:content-type:mime-version:message-id :references:in-reply-to:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=2N7N3DFQuE+aWAvgayOoeK9Kdsr9ItgNWqqp2QW4O6Q=; b=MPwO8Bira+MnCLTG2+meuXyJgBoX/aR8NIRK4npBhLQnomhf6wYc1yTWRm6PiAIcv0 yMkrjvaS7IP1VTSsNBIz4IPTQsmkDmVXa4viidIVJCzlsqruDM9b4nq8zDmyk/U67Fu5 UaAlTTiITE5ZkW7sA0FtUofYArvX0kEGqWjR/Kb2pFZ2lE611ExaYpr11dQ8IcvPlezW H9LAubLJUtVv1bHG6rujKLi+WKNebqDna3akLEQj/YA0aBR2NaVg3sekg2N/sAuHAqYb 7MT5AeEt3mDNbDkjsrKBwuFeyvXVKCIt2zSOEMw7IjONbdiEwy8fShzu32uyDcCEsd4C IKXQ== X-Forwarded-Encrypted: i=1; AKwUvByuhNt6Eplzi9dJeTscCX90lleMWf8zqjol5XiQ5II4yPuLx5l0vghRujTogzt6hKXMLmZ4WX66F0E58K5n0VNZfbI=@vger.kernel.org X-Gm-Message-State: AFuF++kiqrsefhk9O3ShBfciDUuZ1Jr/g+zShI7MHgOFuUZS1f3NrHfe WX9SrGLhRtLLOw/3VhbWh9jqUfLCaRoy1rvbqDQ8G0bTqzbD/LnZ+zaMgL6W5skR1dC10y4aLtH 6LlwDpdVQMleIthS509ffNem4Jn5YywLZ7lchpbn1cV7US53A5FdHOcU8q4tBRYKjSHoKuCkEEA == X-Gm-Gg: AYBFou3bNA+imDpeqBoE2aNogfNAQYgkIcury9yDFnqh5CjepDfP605vNCN4CRWx0vr 2XsdngXLt6lb52tGhzMbYLvAS/MdstJ/Dnm+YOvvYQhnm43FepP88SoRRu/6G3kTAHteKK/VQ3I zGm+hFXkIOrVWcLFd5D/tIOg+rhhyzAcL0hvmYPydoH2grDubP3yA37UnJts3OwACKO6SLg7aQk h7bqah8SaKprmJesFX5+VEZBl3ceXDCas/x/KcXPQxWM3dSKjlVltwul5YIHdClEH9KKbLy3Kdo f6dBnuqyc24ur2KyM5Vb+Q5jpbzX3xHaivxJtnMQRZYauPobAu05ExL+TLwllGbM3GlaIzSxsQl U7yuu+fycAw== X-Received: by 2002:a05:600c:4585:b0:49c:fc6c:be16 with SMTP id 5b1f17b1804b1-49cfea09f08mr58738645e9.28.1788585435736; Fri, 04 Sep 2026 22:17:15 -0700 (PDT) X-Received: by 2002:a05:600c:4585:b0:49c:fc6c:be16 with SMTP id 5b1f17b1804b1-49cfea09f08mr58738395e9.28.1788585435425; Fri, 04 Sep 2026 22:17:15 -0700 (PDT) Received: from ehlo.thunderbird.net ([195.174.135.130]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49cee80eda4sm200070045e9.15.2026.09.04.22.17.14 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 04 Sep 2026 22:17:15 -0700 (PDT) Date: Sat, 05 Sep 2026 04:53:35 +0000 From: Gabriele Monaco To: Alexei Starovoitov , Steven Rostedt CC: Nam Cao , LKML , linux-trace-kernel , bpf , Wen Yang , Tobias Schaffner , Viktor Malik , Linus Torvalds Subject: Re: [RFC PATCH 00/20] rv: Add support for BPF monitors In-Reply-To: References: <20260831090524.106845-1-gmonaco@redhat.com> <87se3sakgi.fsf@yellow.woof> <20260903090211.50d15220@gandalf.local.home> <20260904074317.01b2c0e1@robin> <20260904123108.1fa1d815@gandalf.local.home> <20260904132421.111c0279@gandalf.local.home> <20260904194620.0c7a8363@gandalf.local.home> <20260904201741.2986efca@gandalf.local.home> Message-ID: <228FE969-EBFF-4B60-B0E7-C1E4FD82FB8B@redhat.com> Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-MFC-PROC-ID: 2qfuBEDqpwGcKBV5FvNta9UyUJBFs6H2KwNQpQucclM_1788585436 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Il 5 settembre 2026 00:22:01 UTC, Alexei Starovoitov ha scritto: >On Fri, Sep 4, 2026 at 5:16=E2=80=AFPM Steven Rostedt wrote: >> >> On Fri, 4 Sep 2026 16:48:55 -0700 >> Alexei Starovoitov wrote: >> >> > On Fri, Sep 4, 2026 at 4:45=E2=80=AFPM Steven Rostedt wrote: >> > > >> > > On Fri, 04 Sep 2026 16:34:00 -0700 >> > > "Alexei Starovoitov" wrote: >> > > >> > > > bpf in 2022 was surely less capable then it is today. >> > > > It took us 2 years of bpf core development to statisfy sched-ext d= emands >> > > > and we're still adding new features for sched-ext needs. >> > > > If you're trully willing to remove 90% of kernel/trace/rv/ and ref= actor >> > > > it into tiny shim where all of the core pieces are bpf driven we c= an >> > > > certainly work together (like we did with sched-ext) and add whate= ver >> > > > is missing on bpf side. Then all existing monitors will become bpf= programs. >> > > > But adding bpf as another 'monitor', sorry but hard NO. >> > > > If hardcoded monitors was a mistake then admit it and fix it by de= leting it, >> > > > if it's not a mistake then keep adding hardcoded monitors. Alexei, what I read from your opinion is: if you really want to do this RV = thing, then you should just implement it all in BPF. Please correct me if I'm wrong, but I don't see how this series isn't a ste= p towards it. I am obviously open to all sorts of criticism on /how/ I'm do= ing it. We are adding the possibility to write (existing or new) monitors in BPF, n= ot adding another fat "bpf monitor". And if you believe my attempt to have in-kernel and BPF monitors coexist is= a waste of time, I get that too and I'm open to discuss. As you mentioned, when the project started, BPF was just not ready. My inte= ntion with this series is to reassess this today. RV was initially built with the functional safety use-case in mind. For var= ious technical reasons this didn't take off, but that scenario drove toward= s implementing RV reactors like the panic() one. Something BPF just shouldn= 't do, as I get it. The interoperability with other tools (via RV-generated tracepoints) was al= so a driving factor, together with Daniel probably being more proficient wi= th those back then. That's just from the top of my head: there are historical and technical rea= sons for why RV looks like it is today, whether those are valid or just "mi= stakes" is simply not for us to say. I'd rather discuss on what is the best approach /today/. And that's precise= ly why I submitted the talk for LPC. Gabriele