From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f200.google.com (mail-pg1-f200.google.com [209.85.215.200]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DE0D438758D for ; Thu, 27 Aug 2026 19:02:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.200 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787857376; cv=none; b=YF8LlJr45ep/amaypKkt/S5SGNxH96n7uUlLdlPqBTFfpR+acu/BrqBSiYpDPVZB46UPJck0l8+Hc1l++Bmd5r9wAS/1xNqDgK2r2d2FjHiLGIANakEb4OJSPOUo2vcOCyR2KKzzyoACT9G+P0lLRmfii2kfEecWN3sM7dmx3V4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787857376; c=relaxed/simple; bh=9lVDLbum0cYGjweomvuk0/pgIbbEUjezvszkJrcLLfk=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=g7oyOGCZuVZ+kYelt5xMRlcMVQ8qaJqI6nwFv4bfAEEeBcellxYCxdVB7z85oUZthAxMx2DhMOTHy5c8wmVoqdPc6vaWaxOageuKsMMEKgZtBxu5mJWO52LvVcQdXbdIzrTUxs8C0zAt6uG2DZE99InY5tGi6v2N2X0QlObax4c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=PTLuAgE/; arc=none smtp.client-ip=209.85.215.200 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="PTLuAgE/" Received: by mail-pg1-f200.google.com with SMTP id 41be03b00d2f7-cc1c5810451so291358a12.1 for ; Thu, 27 Aug 2026 12:02:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1787857374; x=1788462174; darn=vger.kernel.org; h=content-transfer-encoding:content-type:cc:to:from:subject :message-id:references:mime-version:in-reply-to:date:from:to:cc :subject:date:message-id:reply-to:content-type; bh=jz9Q8lzA8kr9Cui0qigAU1tqPWkdoLyFdmY0G7Yt6rM=; b=PTLuAgE/60cxXlouWIwv5oZPv6JK5nXoIyXh79kD3br0wD66PcEMs4sXz+kPKG58js i0/liVdnJR+r7/tr0+r3ZqDee0uh+u2XO+XUC0Pnrt9u6hg2HDbH/L/Vf4xdkDjr6uuR EDoxRoSIhMyTrBlRPj7h0pKncYjjfVpTwB13YVsM6SiC0ObaZSQqzj/4aDFjTfLnqPfU p1sWMsy3NP7s6iR3kWmcjM0jbg9HkQMAHHuc8w5ddMlAo5Tz/0S6HdxOuIOKMokFn33R TGd14CffOhc05ToEnKSUGYO97I5DIcZvcVQMiHDOMZCh3YNcOl6VvIvhCDJb47dcadTF 1qcg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1787857374; x=1788462174; h=content-transfer-encoding:content-type:cc:to:from:subject :message-id:references:mime-version:in-reply-to:date :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=jz9Q8lzA8kr9Cui0qigAU1tqPWkdoLyFdmY0G7Yt6rM=; b=Odt9WrqBjEy8ZzA7KJi17DAdLYmv/Ha8Aj508F5OEJOpZ5AbjHITwDPweRxLQFoBYX GebdaG3BQYSYzSMerU6tcQVt0Iy1upaBsyFTMNIwM19rtfVRfdnQGGkkl0LzBZzBoms5 vrArRc+TPrWHI563kJ5If8GJeKyQfRyOXCUWCO0hNhphfafb1fVGd+vUDb7E4ckDO2zD n8MJFLKd7IAT4YEdYph+xUX8PplL9AfvYEHI27t6IL08vCXlFR2gpq4zUg+Ar9Gz76ew r+nYaj9HnU3yW2b3c00rldpVRLma1HEG9uxNot+ZY08aXLsNWnOAkIPrZjm7JT76jWAD OxPw== X-Forwarded-Encrypted: i=1; AHgh+Rr9tN+RKAGSm4XuVHnA97YgVQC4cqcm/gxI4PRllXt4KCtn4Hl9s8p393+Cav3B6NWjDoA=@vger.kernel.org X-Gm-Message-State: AFuF++lZqX/dv2fIrIQX0BuqYtbP1hz6YWarEkzAoB32QA7BVl/2Mzbi RkPegYOXyblZusYAOpJrXxkMBp159/nfpmEGfXvVPhMZqhaiX2EnqnWFUJG1xLzRTVupHP6w8cp MX5to6g== X-Received: from pfqf3.prod.google.com ([2002:aa7:9d83:0:b0:84f:7ce1:5801]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:3021:b0:853:2ca8:c42d with SMTP id d2e1a72fcca58-856297300f5mr2702720b3a.2.1787857373608; Thu, 27 Aug 2026 12:02:53 -0700 (PDT) Date: Thu, 27 Aug 2026 12:02:52 -0700 In-Reply-To: <575b25a59231cfb7bc5fbaf4bbe45bfedad1e3a9.camel@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <827b213a9482b417abb1d172438f0fdbfecd4c7c.camel@intel.com> <575b25a59231cfb7bc5fbaf4bbe45bfedad1e3a9.camel@intel.com> Message-ID: Subject: Re: Process for doing early internal type review on the list From: Sean Christopherson To: Rick P Edgecombe Cc: "pbonzini@redhat.com" , Dave Hansen , "kas@kernel.org" , "kvm@vger.kernel.org" , "x86@kernel.org" Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Thu, Aug 27, 2026, Rick P Edgecombe wrote: > Arg, fix Kiryl's email address. >=20 > On Wed, 2026-08-26 at 16:59 -0700, Rick Edgecombe wrote: > > Sean has long been pushing TDX developers to review less internally and= capture > > everything on the list. For several reasons: > > - Avoid thrash by hashing out things internally that are just overturn= ed later. > > - Capture all the design decisions in lore history. > > - Help developers grow by getting comfortable working and making mista= kes in=C2=A0 =20 > > public. > > - A strong personal conviction that through some confluence of intangi= bles, > > working in public produces better outcomes for the kernel? As evidence, I submit the myriad historical KVM commits with godawful chang= elogs and no meaningful on-list review/discussion. When things go wrong, knowing= the intent and being able to retroactively assess the review process that yield= ed the final commit is extremely valuable. E.g. KVM added 600+ lines of code to (very poorly) virtualize MTRR memtypes= , and carried it for more than 15 years, all because of misdiagnosed #MC issues t= hat showed up in early EPT + VTd enabling. Even with the few breadcrumbs provided by on-list review, it took me for fr= eaking ever to piece together what happened[*]. If all of the review had been don= e in private, and all we saw was the final result, then it's entirely possible w= e'd still be carrying the MTRR virtualization horrors. Another way to look at it: would anyone (seriously) argue that changelogs a= re a waste of time? People can read the code, why do we need to explain what it= does and why? Because anytime future developers are forced to make assumptions = or guesses due to lack of information, the probability of a mistake being and/= or a bug being introduced goes up. And has been proven a hilarious number of ti= mes this year by AI, humans make a lot of mistakes, and the more information th= at's available, the easier it is to decipher and remedy those mistakes. "Documenting" mistakes is also extremely valuable for helping others avoid = those same mistakes. E.g. look at all the bajlilion edge cases and wrinkles Sash= iko is pointing out. Having a public record of exactly what can go wrong, or what= sharp edges exist, is a huge benefit to future developers. How many times have f= olks ended up on Stack Overflow trying to figure out how to do some obsurce thin= g with e.g. inline asm? This is the same thing, just specific to the kernel. It'= s a public, searchable record of potential/common issues and in many cases, the= cures for those issues. [*] https://lore.kernel.org/all/20240309010929.1403984-2-seanjc@google.com