difference between hard float and soft


12 posts
by jakebpg » Mon Oct 01, 2012 8:07 pm
What's the difference between the hard float and the regular image on the download page?

Never heard the term hard float before and am just wondering.

Thanks in advance
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by joan » Mon Oct 01, 2012 8:14 pm
Hard float just means the floating point calculations are done by on chip hardware rather than being emulated by software.
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by Mr.Dave » Mon Oct 01, 2012 8:19 pm
Easy to remember:

Soft=Slow
Hard=Fast
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by jakebpg » Mon Oct 01, 2012 10:12 pm
Thanks guys.

As I said never heard the term before in my15+ years in the IT industry
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by redhawk » Mon Oct 01, 2012 11:43 pm
Hard float and soft float is pretty much comparable to Intel based machines performing float point calculations in hardware (80x87 maths co-processor) or using software (float point emulation).
Hardware float point calculations will win every time on speed, however if you processor cannot float or perform this correctly i.e. Cyrix 486 or early Pentiums then software emulation is a life saver :)

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by pepedog » Tue Oct 02, 2012 9:27 am
Aside from hardware differences, on the rpi archlinuxarm soft boots to command prompt in 24 seconds, hard in 10.
Probably most of the gain is from changing from init to systemd.
x86 stuff I have played with that is without co-processor are 8086, 386, 486SX, don't know about my Pentium60
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by mikerr » Tue Oct 02, 2012 9:49 am
About 10x
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by tawalker » Thu Oct 04, 2012 9:01 am
pepedog wrote:Aside from hardware differences, on the rpi archlinuxarm soft boots to command prompt in 24 seconds, hard in 10.
Probably most of the gain is from changing from init to systemd.
x86 stuff I have played with that is without co-processor are 8086, 386, 486SX, don't know about my Pentium60


I've just done a fresh install of "hard float" Arch/ARM on my Pi, and it configured itself to use systemd instead of initscripts. The system does seem to boot and run noticeably faster than the old "soft float" version, and I suspect systemd may play a part in that.

Even though I'm trying XFCE this time around (I used Fluxbox on the old install), performance feels smoother and quicker - wonder how fast Fluxbox will run on this setup?
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by mrhobbeys » Thu Oct 04, 2012 8:45 pm
From the sounds of it no one should ever use soft float?
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by pepedog » Fri Oct 05, 2012 12:23 am
V5 soft float will remain, there are other (headless) arm devices that are speedier than the raspberrypi, Linux is about choice
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by billb » Fri Oct 05, 2012 1:20 am
When building from source are there any particular flags we should set for hard float? Or is this taken care of automatically? (I'm using Raspbian wheezy)
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by pepedog » Fri Oct 05, 2012 9:23 am
If you use makepkg, it's taken care of.
Flags are in /etc/makepkg.conf
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