From owner-freebsd-current@freebsd.org Sat Feb 23 19:04:11 2019 Return-Path: Delivered-To: freebsd-current@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 63E2415012A3 for ; Sat, 23 Feb 2019 19:04:11 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: from mail-qt1-x836.google.com (mail-qt1-x836.google.com [IPv6:2607:f8b0:4864:20::836]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 6C5226AD76 for ; Sat, 23 Feb 2019 19:04:10 +0000 (UTC) (envelope-from wlosh@bsdimp.com) Received: by mail-qt1-x836.google.com with SMTP id d2so6240515qti.11 for ; Sat, 23 Feb 2019 11:04:10 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bsdimp-com.20150623.gappssmtp.com; s=20150623; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=dOU0vRQ/W5I5+ZNFneJX181UmEyH0BNH0Ryb1x3SREY=; b=yofz9r+dD+R2JMMogpT2hxvI55ZmF4emAMmV5vDYSmR3oQGbxx7TCt29M07eb9/plS nhowqHLEguR1hNEu6lW0P+OObuN/ly7+HLgK3nW9byJt3QvDF9vQVF3E83EzJ7nYF1cs R1x6atlcxmJzAO/dnNnEcfmZsVhhBgo7cCn3iZHJvWoULXDiELRxtqaaPq9XxobhuGd/ ZYbCnVBrZlHU00YMpQIYhzQlrwEp17t7u0N3MgiPYzFfkrNX9jdptd8rIdCaFuHrVlfB rR51N0leo/UgMSZx1W6g/HoT7YxstugCeYAl/+/MP5/CWg/YpTJp2EnM79Qua12k+X6b +rcA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=dOU0vRQ/W5I5+ZNFneJX181UmEyH0BNH0Ryb1x3SREY=; b=DpIaTiJykXfw1GmG1u9j1mgfqHAyfHt3QB4nlmAaeI1PFGIQkMcswjLS/4zzQgl6d5 XqdcXUENhQScPb31D6tP6SZiTSUP/lYSd+DJUflGHu0TmCx90K3FbAVwZdjVVUN660Qp xjAGBiwKxHLA6UUKKHXrOAE1f4RYP0vQwaJjXRnc+lMtNaO9/8j/cS1f6Xzg0diB+izE rC0ZhaoE3VGi0+h4n3L+XBiAG9njESwZM8LSKsTrCoS1RHlkuRtZelWLBlOi6teDoWUY bRlvom1yoabePiNMesjQw8J4v7wyWUmaJydKDYtef1F7QLjROqv26wwIoIGGWb1m7NTZ xPrQ== X-Gm-Message-State: AHQUAuYu4RyDf5I0yUx9TMssOZVwc2HV4uICj1/awe9ycWmX2Xfi8+N7 z+dVIfE77cI07dueY7L7miR+XbA6S8/vGhjIk5oXoQ== X-Google-Smtp-Source: AHgI3IbusW7bXj78b/BGoOq67sRSA3xKe8RT7sDNsE+G8WsGvrEkUdyLg+aYWPuQTf07eV0e7q19Ks6KenzBzakiKEY= X-Received: by 2002:aed:3964:: with SMTP id l91mr8053587qte.33.1550948649765; Sat, 23 Feb 2019 11:04:09 -0800 (PST) MIME-Version: 1.0 References: <20190222033924.GA25285@troutmask.apl.washington.edu> <20190222060410.GA25817@troutmask.apl.washington.edu> <20190223032644.GA14058@troutmask.apl.washington.edu> <20190223091931.GE2420@kib.kiev.ua> <20190223163619.GA18805@troutmask.apl.washington.edu> In-Reply-To: <20190223163619.GA18805@troutmask.apl.washington.edu> From: Warner Losh Date: Sat, 23 Feb 2019 12:03:58 -0700 Message-ID: Subject: Re: r343567 aka PAE vs non-PAE merge breaks i386 freebsd To: Steve Kargl Cc: Konstantin Belousov , FreeBSD Current , Peter Holm , Mark Johnston X-Rspamd-Queue-Id: 6C5226AD76 X-Spamd-Bar: ----- Authentication-Results: mx1.freebsd.org; dkim=pass header.d=bsdimp-com.20150623.gappssmtp.com header.s=20150623 header.b=yofz9r+d X-Spamd-Result: default: False [-5.58 / 15.00]; ARC_NA(0.00)[]; NEURAL_HAM_MEDIUM(-1.00)[-1.000,0]; R_DKIM_ALLOW(-0.20)[bsdimp-com.20150623.gappssmtp.com:s=20150623]; FROM_HAS_DN(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; NEURAL_HAM_LONG(-1.00)[-1.000,0]; MIME_GOOD(-0.10)[multipart/alternative,text/plain]; PREVIOUSLY_DELIVERED(0.00)[freebsd-current@freebsd.org]; DMARC_NA(0.00)[bsdimp.com]; RCPT_COUNT_FIVE(0.00)[5]; TO_MATCH_ENVRCPT_SOME(0.00)[]; TO_DN_ALL(0.00)[]; DKIM_TRACE(0.00)[bsdimp-com.20150623.gappssmtp.com:+]; MX_GOOD(-0.01)[ALT1.aspmx.l.google.com,aspmx.l.google.com,ALT2.aspmx.l.google.com]; RCVD_IN_DNSWL_NONE(0.00)[6.3.8.0.0.0.0.0.0.0.0.0.0.0.0.0.0.2.0.0.4.6.8.4.0.b.8.f.7.0.6.2.list.dnswl.org : 127.0.5.0]; NEURAL_HAM_SHORT(-0.92)[-0.923,0]; R_SPF_NA(0.00)[]; FORGED_SENDER(0.30)[imp@bsdimp.com,wlosh@bsdimp.com]; MIME_TRACE(0.00)[0:+,1:+]; RCVD_TLS_LAST(0.00)[]; ASN(0.00)[asn:15169, ipnet:2607:f8b0::/32, country:US]; FROM_NEQ_ENVFROM(0.00)[imp@bsdimp.com,wlosh@bsdimp.com]; IP_SCORE(-2.64)[ip: (-8.53), ipnet: 2607:f8b0::/32(-2.63), asn: 15169(-1.99), country: US(-0.07)]; FREEMAIL_CC(0.00)[gmail.com] Content-Type: text/plain; charset="UTF-8" X-Content-Filtered-By: Mailman/MimeDel 2.1.29 X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 23 Feb 2019 19:04:11 -0000 On Sat, Feb 23, 2019 at 10:57 AM Steve Kargl < sgk@troutmask.apl.washington.edu> wrote: > Supposely, the laptop only has 4 GB of memory. Not sure how > it finds memory above 4 GB. > Some older chipsets had a 'hole' in memory that they mapped the PCI bus into and then remapped RAM in that range up above the 4GB boundary. That's how it can find memory above 4GB when you have only 4GB of RAM. I hit it with the PC Card stuff I did back in the day since it broke certain heuristics I had in the code that turned out to be unwise for many reasons (not just this one). I don't recall all the details, since it's been so long ago. So I think kib@ is right when he highlights > +0x0000000100000000 - 0x000000011ffe7fff, 536772608 bytes (131048 pages) as the memory, since this is indeed above the 4GB limit. It's about 128k of 4k pages (just shy of the 131072 I'd expect), which is a surprisingly round number. Also one that's easy to implement in hardware. So it certainly "smells" the same... That's why I agree with others that hw.above4g_allow=0 is worth a shot, for at least diagnostic purposes. This memory wasn't used before and if it's used now by the drm drivers, and those aren't PAE safe (meaning they cope with allocations beyond 4GB), then that's quite useful to know. Or maybe it's a different driver hating things and stomping on video memory due to wrap around. Warner