[lkml]   [2011]   [Mar]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
    SubjectRe: PATCH: Add --size-check=[error|warning]

    (resend, fixed the To line)

    * Alan Modra <> wrote:

    > On Mon, Mar 14, 2011 at 10:55:34AM +0100, Ingo Molnar wrote:
    > > The thing is, it is absolutely, breath-takingy incompetent for
    > kernel developers to write such poor asm! And not notice the error
    > for 4 years! [...]

    It is not 'poor asm'.

    The 'bug' is just a slight assymetry in ENTRY()/END() debug-symbols sequences, with
    lots of assembly code between the ENTRY() and the END(). Here's an example:

    ENTRY(xen_do_hypervisor_callback) # do_hypervisor_callback(struct *pt_regs)

    Human reviewers almost never catch such small mismatches, and binutils never even
    warned about it either - for over a decade.

    Now kernel bisections are insta-broken on latest binutils, and there's nothing to do
    about it on the kernel side as during bisection all later fixes are unfolded. The
    fix itself i already applied - but my argument was not about that:

    > [...] Oh, and the binutils developers to write such a poor assembler in the first
    > place. ;-)
    > Seriously, you are complaining because something is fixed??

    No, i reported this bug because the kernel build gets broken going back 130,000
    commits, breaking bisection and causing other damage - while issuing a warning
    message would achieve the same effect of warning the developer about the mismatch.

    > > The correct solution is to turn it into a warning as me and others have suggested.
    > I disagree. The whole world is not the linux kernel. I think HJ is
    > bending over backwards to even offer a switch that turns the error
    > into a warning.

    It's not about a switch at all - it's to not break builds by default. I.e. the
    default behavior should be to issue a warning and ignore the directive.

    This is a very simple concept of compatibility: the build environment should always
    be very permissive - stuff that build fine before should be allowed to build.

    Also, i hope you are not suggesting to break projects just because they are not
    important to you personally? The fix is exceedingly simple to do for the binutils
    project - and impossible to do for the kernel project (because during bisection -
    which is a very powerful debugging tool - older versions of the source get checked



     \ /
      Last update: 2011-03-14 13:29    [W:0.023 / U:49.220 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site