Date: Tue, 05 Oct 2010 00:37:47 +0100 From: spellberg_robert <emailrob@emailrob.com> To: Dan Nelson <dnelson@allantgroup.com>, fbsd_questions <freebsd-questions@freebsd.org> Subject: Re: [fbsd_questions] i386 vs amd64, on intel_64 Message-ID: <4CAA654B.7040409@emailrob.com> References: <4CAA3030.3090001@emailrob.com> <AANLkTintm_XubwCCRNJci99Y4M6nwbFr=oiKqBw2%2Ba9M@mail.gmail.com> <4CAA3CFE.1060609@emailrob.com> <AANLkTi=e8cBqd6Z=zxOxpMZm_RD=-RODupzprK843=qF@mail.gmail.com> <20101004225757.GK40148@dan.emsphone.com>
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well, i looked at questions back to the beginning of august.
on aug_09 i found a thread that suggests the following questions.
for a given release of freebsd,
q: is it that the version labeled "i386" contains only 32_bit headers and source,
which creates the 32_bit version of freebsd, as well as 32_bit versions of what i write,
which will run as 32_bit code on either i_386, intel_64 or amd_64 ?
q: is it that the version labeled "amd64" contains only 64_bit headers and source,
which creates the 64_bit version of freebsd, as well as 64_bit versions of what i write,
which will run as 64_bit code on the intel_64 and the amd_64, but, not the i_386 ?
q: if a "i386" version is installed on an intel_64 platform,
then the pointers are 32_bits_wide, no matter what ?
q: if i want to produce both 32_bit and 64_bit versions of my "killer_app",
then i need two machines,
one a 32_bit or a 64_bit running "i386",
the other --only-- a 64_bit running "amd64" ?
q: given that i have intel_64 hardware,
do i need to start acquiring the "amd64" versions of the releases,
rather_than / in_addition_to the "i386" versions ?
q: given that --i-- am committed to 64_bit hardware,
perhaps, i should give up on the "i386" versions of the releases and
require my users to spend us$_300 on 64_bit hardware
[ it would save a large number of conditional_compilation directives;
nudge_nudge, wink_wink, say no more
] ?
again, i thank you for your assistance.
rob
Dan Nelson wrote:
> In the last episode (Oct 04), David Brodbeck said:
>
>>On a 64-bit system, if you build a binary with the -m32 flag, it
>>should run on both i386 and x86-64 systems. A binary built with -m64
>>will only run on x86-64. Does that help?
>
>
> Actually, -m32 on amd64 won't generate usable binaries, since
> /usr/include/machine/* are all amd64 headers and you end up with things like
> struct FILE with wrong-size elements. There was a thread a few weeks ago
> discussing this. If you need to generate 32-bit executables, you'll need to
> do it inside an all-32-bit chroot or a virtual machine.
>
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