netdev - Re: [PATCH V11 3/5] printk: hash addresses printed with %p

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Message-ID: <CAMuHMdV4R9ngCiho0BuDkQ2K4ivVaDHs6pxkEdj2q=J=H0RXOA@mail.gmail.com>
Date:   Wed, 6 Dec 2017 09:48:12 +0100
From:   Geert Uytterhoeven <geert@...ux-m68k.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
Cc:     "Tobin C. Harding" <me@...in.cc>,
        "kernel-hardening@...ts.openwall.com" 
        <kernel-hardening@...ts.openwall.com>,
        "Jason A. Donenfeld" <Jason@...c4.com>,
        "Theodore Ts'o" <tytso@....edu>, Kees Cook <keescook@...omium.org>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Tycho Andersen <tycho@...ho.ws>,
        "Roberts, William C" <william.c.roberts@...el.com>,
        Tejun Heo <tj@...nel.org>,
        Jordan Glover <Golden_Miller83@...tonmail.ch>,
        Greg KH <gregkh@...uxfoundation.org>,
        Petr Mladek <pmladek@...e.com>, Joe Perches <joe@...ches.com>,
        Ian Campbell <ijc@...lion.org.uk>,
        Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Catalin Marinas <catalin.marinas@....com>,
        Will Deacon <wilal.deacon@....com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Chris Fries <cfries@...gle.com>,
        Dave Weinstein <olorin@...gle.com>,
        Daniel Micay <danielmicay@...il.com>,
        Djalal Harouni <tixxdz@...il.com>,
        Radim Krčmář <rkrcmar@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Network Development <netdev@...r.kernel.org>,
        David Miller <davem@...emloft.net>,
        Stephen Rothwell <sfr@...b.auug.org.au>,
        Andrey Ryabinin <aryabinin@...tuozzo.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Subject: Re: [PATCH V11 3/5] printk: hash addresses printed with %p

Hi Linus,

On Wed, Dec 6, 2017 at 12:33 AM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
> On Tue, Dec 5, 2017 at 2:57 PM, Geert Uytterhoeven <geert@...ux-m68k.org> wrote:
>> Lowest 3 is good enough for all natural types, up to long long.
>> We may still receive complaints from people who care about seeing if
>> a pointer is cacheline-aligned or not. Fixing that may need up to 7 bits, I'm
>> afraid, which is a bit too much to give up.
>
> I really think even the lowest three is a bit too much.
>
> Who really cares? If it's something that is particularly _about_
> alignment (ie an alignment trap), maybe just print out those bits
> separately.

If I'm not mistaken, some architectures don't generate alignment traps, but
just zero the LSBs.

> And for everything else? It's purely about getting used to it.

Yes, we will get used to it.

I agree that for debugging during development, we will just use %px and be
fine.

Storm in a glass of water, everybody will have forgotten by the time v4.16 is
released.

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@...ux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds