Just to update on some off-forum activity re this thread:
Tux expressed the view that hints/linux.sh should be amended so that -Duse64bitall would create the build I was looking for (ivtype of long, ivsize of 8, ptrsize of 8 and -m64 in ccflags).
But we couldn't get that set correctly. He didn't have access to a powerpc64 system, and my capability with shell scripting is very limited. (More accurately, any such capability is yet non-existent.)

In the midst of this hackery, I found that -m64 needs *also* to be included in cppflags, ldflags and lddlflags.
Eventually I was able to get the build I was after by leaving hints/linux.sh in its original state and running: 
sh Configure -des -Dccflags=-m64 -Dldflags=-m64 -Dlddlflags="-m64 -sha
+red -O1" -Dcc=gcc

[download]
That is essentially the same perl as I had been getting with: 
sh Configure -des -Dcc="gcc -m64"

[download]
The only difference being that "-m64" was removed from cc, and was inserted into the various flags, as needed - exactly as I was seeking !!
Other than that, the perl -V outputs were identical (with ivtype=long, ivsize=8 and ptrsize=8).

However, it didn't help with the problem that had triggered this investigation.
And, when I think about it again, it's probably not surprising that it did make no difference.
AFAICT, operating in 64-bit mode requires that whenever "gcc" is called, "-m64" must also be called, and having a compiler named "gcc -m64" therefore looks to be a very sane way of ensuring that happens.

Anyway, it sure is good to have the alternative that I was seeking and I'll keep such a build of perl handy for reference.
(But I'm currently planning on staying with the -Dcc="gcc -m64" builds for as long as they don't prove to be deficient.)

Cheers,
Rob

In reply to Re^3: [Linux] Controlling 32-bit mode vs 64-bit mode by syphilis
in thread [Linux] Controlling 32-bit mode vs 64-bit mode by syphilis

Title:
Use:  <p> text here (a paragraph) </p>
and:  <code> code here </code>
to format your post, it's "PerlMonks-approved HTML":


  • Posts are HTML formatted. Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!
  • Titles consisting of a single word are discouraged, and in most cases are disallowed outright.
  • Read Where should I post X? if you're not absolutely sure you're posting in the right place.
  • Please read these before you post! —
  • Posts may use any of the Perl Monks Approved HTML tags:
    a, abbr, b, big, blockquote, br, caption, center, col, colgroup, dd, del, details, div, dl, dt, em, font, h1, h2, h3, h4, h5, h6, hr, i, ins, li, ol, p, pre, readmore, small, span, spoiler, strike, strong, sub, summary, sup, table, tbody, td, tfoot, th, thead, tr, tt, u, ul, wbr
  • You may need to use entities for some characters, as follows. (Exception: Within code tags, you can put the characters literally.)
            For:     Use:
    & &amp;
    < &lt;
    > &gt;
    [ &#91;
    ] &#93;
  • Link using PerlMonks shortcuts! What shortcuts can I use for linking?
  • See Writeup Formatting Tips and other pages linked from there for more info.