From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on inbox.vuxu.org X-Spam-Level: X-Spam-Status: No, score=-0.3 required=5.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HTML_FONT_LOW_CONTRAST,HTML_IMAGE_ONLY_20,HTML_MESSAGE, MAILING_LIST_MULTI,RCVD_IN_DNSWL_NONE,URIBL_SBL_A autolearn=ham autolearn_force=no version=3.4.4 Received: (qmail 4983 invoked from network); 21 Feb 2021 22:55:10 -0000 Received: from minnie.tuhs.org (45.79.103.53) by inbox.vuxu.org with ESMTPUTF8; 21 Feb 2021 22:55:10 -0000 Received: by minnie.tuhs.org (Postfix, from userid 112) id 193DA9CAB4; Mon, 22 Feb 2021 08:55:08 +1000 (AEST) Received: from minnie.tuhs.org (localhost [127.0.0.1]) by minnie.tuhs.org (Postfix) with ESMTP id ADDEC93D39; Mon, 22 Feb 2021 08:54:48 +1000 (AEST) Authentication-Results: minnie.tuhs.org; dkim=pass (1024-bit key; unprotected) header.d=ccc.com header.i=@ccc.com header.b="CoJo+6jG"; dkim-atps=neutral Received: by minnie.tuhs.org (Postfix, from userid 112) id B66B493D39; Mon, 22 Feb 2021 08:54:46 +1000 (AEST) Received: from mail-qt1-f169.google.com (mail-qt1-f169.google.com [209.85.160.169]) by minnie.tuhs.org (Postfix) with ESMTPS id 07CFB93D32 for ; Mon, 22 Feb 2021 08:54:46 +1000 (AEST) Received: by mail-qt1-f169.google.com with SMTP id v3so8066040qtw.4 for ; Sun, 21 Feb 2021 14:54:45 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ccc.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=ssVK1etwxtbFwKKM9HqJJWnRKELzQfT/dTsGAApdANM=; b=CoJo+6jGlQJej8MdEWzWxtp8MVMktjPLOryFxZnqRVLrbS2TUNH1eBJOrCNHW+KeAW PBE21mLZFuwkEDxczShEMkuLPD7xKTw0GK60Zv8YBW9gmHvIIvItdkhotR541tl5QAFV /nXiZkdgzLSSrXupi8F0Xg5h//F+WYE02x5sM= 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=ssVK1etwxtbFwKKM9HqJJWnRKELzQfT/dTsGAApdANM=; b=ouH+iHHr+V+gldqsZjGu0t4Z2tkkQDlt+pIH2AnF8Hr8LlPL1w29ZUYKNj3KjxfAHo J/r0o6MngaQ1+TkU0tlAfZksxTpJyiqYQWeoEkVMGinkY8SCUtDNMtM/9ULT03xB7Rhd Lf5l+jJhXOVpCgJrhUmD3h40xIj0zZSnB5kAfsS5H5+WYcX6we7EebbeRH7SD205VhRP mo/+u+2NndDMPc1a/Ajm/qgAQfYJuwmQGn2HgGqOTuPshoayPAhfhwQ1amMmLOeLdFH2 NHa2U5Byg7oPg6GXl+ICdv/2/DfX5wngUIK3cHbsLsstw3sjr5Q0Kn/X+8UTm1c2MczT 4uog== X-Gm-Message-State: AOAM532VchR19CymhKH0vm4T1IDwv7aOi6G2Gklk4PVS+iwbYidlV2At BmA+9Mjv+SWRCQByKLKYaQcIJSzbG+Id4eLTQ19g9A== X-Google-Smtp-Source: ABdhPJwA8WxiQPqQpoa10Pj8Mr9DrBKidgOnJUyHYGlnXcZ8rMhQxRbH+2AtX7MxjYLzWGUeU/pUcGYetvKE8RW9KjI= X-Received: by 2002:ac8:4c89:: with SMTP id j9mr17590284qtv.354.1613948084880; Sun, 21 Feb 2021 14:54:44 -0800 (PST) MIME-Version: 1.0 References: In-Reply-To: From: Clem Cole Date: Sun, 21 Feb 2021 17:54:19 -0500 Message-ID: To: M Douglas McIlroy Content-Type: multipart/alternative; boundary="000000000000491e3305bbe09233" Subject: Re: [TUHS] Abstractions X-BeenThere: tuhs@minnie.tuhs.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: The Unix Heritage Society mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: TUHS main list Errors-To: tuhs-bounces@minnie.tuhs.org Sender: "TUHS" --000000000000491e3305bbe09233 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Sat, Feb 20, 2021 at 6:10 PM M Douglas McIlroy < m.douglas.mcilroy@dartmouth.edu> wrote: > > - separation of code and data using read-only and read/write file > systems > > I'll bite. How do you install code in a read-only file system? And > where does a.out go? > The best way I have seen this done is with overlay and union file system support. The 'writeable' versions are the file in /bin are overlayed as needed. To do this properly you need the stackable file system stuff we worked on at LCC and Sun. If you can interpose at the inode level it's very cool and flexible (Sun played with - but makes the Sun symlink nightmare seem like an easy night at the movies), at the filesystem switch layer (Locus and UCLA - scheme that was in BSD at one point - easier to manage/admin). =E1=90=A7 --000000000000491e3305bbe09233 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable


On Sat, Feb 20, 2021 at 6:10= PM M Douglas McIlroy <m.douglas.mcilroy@dartmouth.edu> wrote:
>=C2=A0 - separation of code and data u= sing read-only and read/write file systems

I'll bite. How do you install code in a read-only file system? And
where does a.out go?
The best way I have seen this= done is with overlay and union file system support.=C2=A0 =C2=A0The 'w= riteable' versions are the file in /bin are overlayed=C2=A0as needed.= =C2=A0 =C2=A0To do this properly you need the stackable file system stuff w= e worked on at LCC and Sun.=C2=A0 If you can interpose at the inode level i= t's very cool and flexible (Sun played with - but makes the Sun symlink= nightmare seem like an easy night at the movies), at the filesystem=C2=A0s= witch layer=C2=A0(Locus and UCLA - scheme that was in BSD at one= point - easier to manage/admin).


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