From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.90_1) id 1nAJQx-0003R8-GH for mharc-grub-devel@gnu.org; Wed, 19 Jan 2022 17:28:03 -0500 Received: from eggs.gnu.org ([209.51.188.92]:40748) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nAJQv-0003QP-OO for grub-devel@gnu.org; Wed, 19 Jan 2022 17:28:01 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:22718) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1nAJQn-0002ff-SE for grub-devel@gnu.org; Wed, 19 Jan 2022 17:28:00 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642631270; 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: in-reply-to:in-reply-to:references:references; bh=lxxJJ+e77mb7Rpzor6lF5x3lWx7uxgjIEKsKRDlBeFw=; b=S/uXaGUdmwbj1K9pTK5OfmM5jeeTZoNqiEprWHmnCcA++zOvGfuq4+F+zLMt1Lk6YqELvg aEgcCuMod7O30xpRCA4Bp+GSydIdHPVoukvS4sDgoUflM0wqgNgI0GTQE2jU9l12Ig6KiR Ht9AymiCxwpVnwsfG4YCds/PbX++QWE= Received: from mail-qt1-f198.google.com (mail-qt1-f198.google.com [209.85.160.198]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-227-mernjG45NJ-pwRbTSIwsnQ-1; Wed, 19 Jan 2022 17:25:25 -0500 X-MC-Unique: mernjG45NJ-pwRbTSIwsnQ-1 Received: by mail-qt1-f198.google.com with SMTP id f21-20020ac84655000000b002cae5b5722bso2375332qto.10 for ; Wed, 19 Jan 2022 14:25:25 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=lxxJJ+e77mb7Rpzor6lF5x3lWx7uxgjIEKsKRDlBeFw=; b=pOZNEgIh2mqjqZ/vxhXBanlX/vXNr29wmlBhvF80UcKAzxfdfzGNDZlhrRaXHlwRHx GmxxHGfcqzcJbPgu5jWo3s5TM5FUp2Gt+nEtjtvxuN328qwcbD1NEqSSZ37yijRQYVXO NyZCiscrUlsL3tug2+CMFbFA1Brq5Eh9jQ039Q6SelxjlwgB1DJUXGFQsdp3M4910kW7 HnxoIvmO//a53xa3JmNe7fX4LrNlABcVJVt9PfMz+djoFudF2MjCjK3/1EhccU9z8bVK aNIsVNCq2lf+y1DVtnmy/OvdkLDYBHaHuMUcN15xeZXMIYtzaV5+EDKvNWjjiP+qPZCZ i96w== X-Gm-Message-State: AOAM533J7xRL8zLffreZpltmNYzxNbSRBaygLp+g6o4c2eccpsDdbg2A cMfOSdnaBEA1ij9Gvo3yVbz1rpx/ZCZHDkMh1xWGLSE8Byojy+f+4J2I/UslZXkSLX5PnPkRIex sA37b6V1P2zo= X-Received: by 2002:ac8:5781:: with SMTP id v1mr13861969qta.535.1642631124588; Wed, 19 Jan 2022 14:25:24 -0800 (PST) X-Google-Smtp-Source: ABdhPJwgBsLXyy+jtqXT/ed9vD6H1WEzRqCnuQ8nkysy2MSBR/2QDTVR/rzFTPz+1IYetb2gw2IQ8A== X-Received: by 2002:ac8:5781:: with SMTP id v1mr13861923qta.535.1642631123501; Wed, 19 Jan 2022 14:25:23 -0800 (PST) Received: from localhost ([2601:184:4181:74c0:862e:5809:ed9e:e10e]) by smtp.gmail.com with ESMTPSA id 9sm518119qtp.23.2022.01.19.14.25.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 19 Jan 2022 14:25:23 -0800 (PST) From: Robbie Harwood To: Paul Menzel , Javier Martinez Canillas Cc: Peter Jones , Daniel Kiper , The development of GNU GRUB Subject: Re: [PATCH v2] i386: Make pmtimer tsc calibration not take 51 seconds to fail In-Reply-To: <5081629f-11c2-bcaf-544a-7374d4753271@molgen.mpg.de> References: <20200529100837.1054806-1-javierm@redhat.com> <5081629f-11c2-bcaf-544a-7374d4753271@molgen.mpg.de> Date: Wed, 19 Jan 2022 17:25:19 -0500 Message-ID: MIME-Version: 1.0 Content-Type: multipart/signed; boundary="=-=-="; micalg=pgp-sha512; protocol="application/pgp-signature" Received-SPF: pass client-ip=170.10.129.124; envelope-from=rharwood@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -34 X-Spam_score: -3.5 X-Spam_bar: --- X-Spam_report: (-3.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.7, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 19 Jan 2022 22:28:02 -0000 --=-=-= Content-Type: text/plain Paul Menzel writes: > Am 29.05.20 um 12:08 schrieb Javier Martinez Canillas: > >> +/* >> + * Define GRUB_PMTIMER_IGNORE_BAD_READS if you're trying to test a timer that's >> + * present but doesn't keep time well. >> + */ >> +// #define GRUB_PMTIMER_IGNORE_BAD_READS > > So GRUB needs to be rebuild for both cases? Could it be configured at > runtime with a config option, or is the TSC calibration happening too > early? Not an author, but my understanding is that that's a configuration intended for testing only. e.g., from the commit message: > This outcome was tested using grub compiled with > GRUB_PMTIMER_IGNORE_BAD_READS defined (so as not to trip the bad read > test) using qemu+kvm with UEFI (OVMF) firmware, and these options: > -machine pc-q35-2.10 -cpu Broadwell-noTSX which I take to mean that Peter did not have a machine with a timer that misbehaved but didn't return 0 or 0xffffffff, yet wanted a way to test that codepath. This wouldn't be a configuration that I can imagine anyone wanting to ship, so I don't really see value in having it available at runtime. Hope that helps. 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