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    SubjectPATCH: Re: Compilation problem in ndisc.c / 2.5.1-pre2 : possible gcc bug?
    Date
    Brian Gerst (bgerst@didntduck.org) wrote:
    >"Richard B. Johnson" wrote:
    >>
    >> On Wed, 28 Nov 2001, Martin Eriksson wrote:
    >> > From: "Richard B. Johnson" <root@chaos.analogic.com>
    >> > > On 28 Nov 2001, Erik Hensema wrote:
    >> > > > I've been looking into the compile problems of net/ipv6/ndisc.c in
    >> > > > 2.5.1-pre2 and I found that the asm generated by gcc (2.95.3) is wrong:
    >> > > >
    >> > > > This is a small part of a diff betweem two asm files generated by gcc,
    >> > note
    >> > > > the missing \n's in the wrong code:
    >> > >
    [code]
    >> > > This is probably just some loop unrolling, not some as you say "wrong
    >> > > code".
    >> >
    >> > Correct me if I'm wrong, but I don't think "%edxadcl" really assembles....
    >>
    >> No, but an edited 'diff' of the assembly output of a 'C' compiler doesn't
    >> really tell much. Note, no line numbers, no clue as to what the diff
    >> was about. The actual defective section of code would be much more
    >> instructive. For instance, is this as a result of an in-line macro
    >> expansion; the result of a <CR><LF> 'dos' file; the true output of
    >> a 'C' file with no __inline__ __asm__?
    >
    >It's from include/asm-i386/checksum.h, specifically csum_ipv6_magic().
    >The asm statements in this header file need semicolons or explicit
    >newlines after each opcode.

    You're right, that was the problem.

    This patch fixes it:

    --- linux/include/asm-i386/checksum.h.orig Wed Nov 28 21:49:00 2001
    +++ linux/include/asm-i386/checksum.h Wed Nov 28 21:52:28 2001
    @@ -156,17 +156,17 @@
    unsigned int sum)
    {
    __asm__(
    - "addl 0(%1), %0"
    - "adcl 4(%1), %0"
    - "adcl 8(%1), %0"
    - "adcl 12(%1), %0"
    - "adcl 0(%2), %0"
    - "adcl 4(%2), %0"
    - "adcl 8(%2), %0"
    - "adcl 12(%2), %0"
    - "adcl %3, %0"
    - "adcl %4, %0"
    - "adcl $0, %0"
    + "addl 0(%1), %0 ;\n"
    + "adcl 4(%1), %0 ;\n"
    + "adcl 8(%1), %0 ;\n"
    + "adcl 12(%1), %0 ;\n"
    + "adcl 0(%2), %0 ;\n"
    + "adcl 4(%2), %0 ;\n"
    + "adcl 8(%2), %0 ;\n"
    + "adcl 12(%2), %0 ;\n"
    + "adcl %3, %0 ;\n"
    + "adcl %4, %0 ;\n"
    + "adcl $0, %0 ;\n"
    : "=&r" (sum)
    : "r" (saddr), "r" (daddr),
    "r"(htonl(len)), "r"(htonl(proto)), "0"(sum));
    --
    Erik Hensema (erik@hensema.net)
    I'm on the list, no need to Cc: me, though I appreciate one if your
    mailer doesn't support the References header.
    -
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