From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-ed1-f46.google.com (mail-ed1-f46.google.com [209.85.208.46]) (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 77AD230AAA4 for ; Thu, 14 Aug 2025 13:27:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.208.46 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755178066; cv=none; b=WD6XtI91kT9Lo/7MHHD3R7ZNJbxXho4yWt5+1rSsmROP7CraomsU7cYXqdJchN5HsQyzK1CBPGuq1ajZmiTL2ulNnoYP3wU3W5m8eUPaO3RS8ykrvQ1TOSqrfCy29WoYcCZtr2pTWiQYMKJtXNrg7kS5aDPs/oqgf6gyHackETI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755178066; c=relaxed/simple; bh=rKjVUqpwl17P+KMTSKwInqH48WkuPopBFLrzR8IYqTc=; h=MIME-Version:References:In-Reply-To:From:Date:Message-ID:Subject: To:Cc:Content-Type; b=TpFdjo5J7pJTSKMKT8dU+KlT+GBe16HKwmqfJXWX3R3RzfdaNv4kwPd/CCuxX+n0WJnOjtRTkvIfNiqDsMGCDRGOj7fildpbe9zgG4VBXFZZbLCTe9AJrz7aqnx1QETEdIW4nQhzFe1B54o50eUUvUR0l7B52525TFpFnCk6iTI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=h4HHrKOk; arc=none smtp.client-ip=209.85.208.46 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=google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="h4HHrKOk" Received: by mail-ed1-f46.google.com with SMTP id 4fb4d7f45d1cf-617ff2c8e5dso10257a12.0 for ; Thu, 14 Aug 2025 06:27:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1755178063; x=1755782863; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=rKjVUqpwl17P+KMTSKwInqH48WkuPopBFLrzR8IYqTc=; b=h4HHrKOk/liyRwlTPPppmlh/WxNqlJ/rjsHI4+m3QH59nseStSsmr4nijJwvVHPfPU wyIvvdX8POmOuzsWKIU2BxrieIaQlpKvn80cum50pjMucvXMrN2sHgTQONKZK/1G3A0e tFlOEurLpRNT59mNMzBfP262ZAvNCNsq5erG9oYPlBxwBjUPsc5ymUnP/TpK7ppwtnPS mcN+X9Szuqk8y2djPQVURUUwbZzswKYpj7ME2X5DNR69xw6UY/xjAX85yqxuBr14XEs4 v5/npTkrryYL39bKpnHg8kofRE1EVJIJFQkuok9KqkS9Y6Udqb+0p8Ua2FnHGousuPko MoFw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1755178063; x=1755782863; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=rKjVUqpwl17P+KMTSKwInqH48WkuPopBFLrzR8IYqTc=; b=MRePlOjO5M1VpzDK5s8KFZawrMbeychKMH9D4ihY6uEt8wkXscP4lGgXe9oS9VjWe7 y5O3hlTE6SMNoZaUuMSnGJ+gpiY3+6NKwffENrGO6TpcdYjdJAosukcMs6cgJObbLFBF 9jPflTTTVhCK25dDUCozgKdvFBQfwo9yMkEk8B4UPb9st802gw/wfJtbDNoEea9o5Ylv Ud/KyTNGtZmBEzD/mhU7Dd7cfJlb8/4OfDyHj5YZsfogArpwgaUqhr/33aVFtrDyts3i TnBswZU5OCsBzL/QtoF7zdlo6OlwmlzYh4GzXnOJgTSFzQVuh+rjrpCiLiW8fZymWTUG h73g== X-Forwarded-Encrypted: i=1; AJvYcCW1VqTPt2O2kuj9BOBndQ+r/v0ao0GOAiwrGqW+/7pNx5qNdHepjiz+0uJ0QJB6ueliaWUhT1tXjtU=@vger.kernel.org X-Gm-Message-State: AOJu0Yy8JNlBUGnosFn+V7Q2eDbd9HRJ5gNawwvlYO2fZc1dGKr6QtTN 8iZCec2lBtVpKZbIevjd0013qMgpBvHbBOtswxWHGCWCCFMSkHxGl5APUFraHG6zi2geM+/ZgiK VUPvJS0p19d3VGFx9oNFirsvCEipJnBgNxzF+U0W+sKfoeLVtHscPSCNVGIg= X-Gm-Gg: ASbGncuA895b0hNAJy9NNnFazXjfmT/SHS+1PQpQaVQbleXfp+jCTdF1mD0lgb2roSe 8JF+/vzw6t1g9iIw+hE7/d2MVQZ2XqEbAK2sLYTDXtADxmG2f1luQRgEd5tVg/8aaW3enUiPRUQ YHuTXn8E/r1Nk3Zbz76/OfQvqKLS/RsqKDEh4iiqoiAXVsR1bIdJCrU17mm3fKiDGiXUjB4Xi6S Bbqe9SAC9fhwECE9TsoNrLZSk0j8bzfApFasvLCzypNfgGd7Jkk X-Google-Smtp-Source: AGHT+IEu9U0pbzMYFCpXzMGkMdfavpp0q0i1lIx9CK73KOosqb3zwB/n5//3FMTW4AWTjYRn2/rUlEjYnuedieOKxqk= X-Received: by 2002:a05:6402:c1a:b0:617:b4c9:4f90 with SMTP id 4fb4d7f45d1cf-618928d1bcemr49916a12.5.1755178062489; Thu, 14 Aug 2025 06:27:42 -0700 (PDT) Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20250612114210.2786075-1-mclapinski@google.com> <685c67525ba79_2c35442945@iweiny-mobl.notmuch> In-Reply-To: From: =?UTF-8?B?TWljaGHFgiBDxYJhcGnFhHNraQ==?= Date: Thu, 14 Aug 2025 15:27:31 +0200 X-Gm-Features: Ac12FXyHou1fyJhNDgAZDR7CRUt48o6SkCf0niifqm0hDvHBUXmlc4ifrrlM40Q Message-ID: Subject: Re: [PATCH v3 0/2] libnvdimm/e820: Add a new parameter to configure many regions per e820 entry To: Ira Weiny Cc: Jonathan Corbet , Dan Williams , Vishal Verma , Dave Jiang , nvdimm@lists.linux.dev, "Paul E. McKenney" , Thomas Huth , Andrew Morton , Steven Rostedt , "Borislav Petkov (AMD)" , Ard Biesheuvel , Greg Kroah-Hartman , Pasha Tatashin , Mike Rapoport , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-cxl@vger.kernel.org Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, Jul 1, 2025 at 2:05=E2=80=AFPM Micha=C5=82 C=C5=82api=C5=84ski wrote: > > On Wed, Jun 25, 2025 at 11:16=E2=80=AFPM Ira Weiny = wrote: > > > > Michal Clapinski wrote: > > > This includes: > > > 1. Splitting one e820 entry into many regions. > > > 2. Conversion to devdax during boot. > > > > > > This change is needed for the hypervisor live update. VMs' memory wil= l > > > be backed by those emulated pmem devices. To support various VM shape= s > > > I want to create devdax devices at 1GB granularity similar to hugetlb= . > > > Also detecting those devices as devdax during boot speeds up the whol= e > > > process. Conversion in userspace would be much slower which is > > > unacceptable while trying to minimize > > > > Did you explore the NFIT injection strategy which Dan suggested?[1] > > > > [1] https://lore.kernel.org/all/6807f0bfbe589_71fe2944d@dwillia2-xfh.jf= .intel.com.notmuch/ > > > > If so why did it not work? > > I'm new to all this so I might be off on some/all of the things. > > My issues with NFIT: > 1. I can either go with custom bios or acpi nfit injection. Custom > bios sounds rather aggressive to me and I'd prefer to avoid this. The > NFIT injection is done via initramfs, right? If a system doesn't use > initramfs at the moment, that would introduce another step in the boot > process. One of the requirements of the hypervisor live update project > is that the boot process has to be blazing fast and I'm worried > introducing initramfs would go against this requirement. > 2. If I were to create an NFIT, it would have to contain thousands of > entries. That would have to be parsed on every boot. Again, I'm > worried about the performance. > > Do you think an NFIT solution could be as fast as the simple command > line solution? Hello, just a follow up email. I'd like to receive some feedback on this.