Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit quantities on 64 bit archs

From	Linus Torvalds <torvalds@linux-foundation.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit quantities on 64 bit archs
Date	2017-01-19 01:20 +0100
Message-ID	<t18Cl-2D0-1@gated-at.bofh.it> (permalink)
References	(3 earlier) <t0WKU-3x9-55@gated-at.bofh.it> <t0YWm-4Nd-29@gated-at.bofh.it> <t13jk-7zO-11@gated-at.bofh.it> <t13jk-7zO-9@gated-at.bofh.it> <t17dg-1CE-19@gated-at.bofh.it>
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On Wed, Jan 18, 2017 at 2:37 PM, Ard Biesheuvel
<ard.biesheuvel@linaro.org> wrote:
>
> For a ballpark number of 10,000 CRCs in the core kernel, this would
> increase the size of the image by 40 KB for 32-bit architectures (and
> if saving 40 KB is essential, chances are you won't be using
> modversions in the first place).

As you say, I don't think the space issue is much of a problem.

I'm more worried about the replacement of one crazy model that has
problems due to linker subtlety with _another_ one.

Your genksyms.c change is not exactly obvious. I looked at it, and my
brain just shut down. Why both the

  LONG(0x%08lx);

_and_ the

  "%s__crc_%s = 0x%08lx;\n"

in the linker script? I'm sure there's a good reason, but I'd like to
see a more explicit explanation fo what the generated linker script
does and what the rules are.

         Linus

Thread

[PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit quantities on 64 bit archs Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-01-17 20:30 +0100
  Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit  quantities on 64 bit archs Linus Torvalds <torvalds@linux-foundation.org> - 2017-01-18 00:50 +0100
    Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit  quantities on 64 bit archs Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-01-18 12:40 +0100
      Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit  quantities on 64 bit archs Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-01-18 15:00 +0100
        Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit  quantities on 64 bit archs Linus Torvalds <torvalds@linux-foundation.org> - 2017-01-18 19:40 +0100
          Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit  quantities on 64 bit archs Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-01-18 23:50 +0100
            Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit  quantities on 64 bit archs Linus Torvalds <torvalds@linux-foundation.org> - 2017-01-19 01:20 +0100
              Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit  quantities on 64 bit archs Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-01-19 10:40 +0100
                Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit  quantities on 64 bit archs Linus Torvalds <torvalds@linux-foundation.org> - 2017-01-19 18:30 +0100
                Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit  quantities on 64 bit archs Ard Biesheuvel <ard.biesheuvel@linaro.org> - 2017-01-20 13:30 +0100
        Re: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit  quantities on 64 bit archs Linus Torvalds <torvalds@linux-foundation.org> - 2017-01-18 19:40 +0100
        RE: [PATCH v4 3/3] modversions: treat symbol CRCs as 32 bit  quantities on 64 bit archs David Laight <David.Laight@ACULAB.COM> - 2017-01-19 18:10 +0100

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