Soft-float version of Raspbian does not boot - boot

Question

I downloaded the hard float image of Raspbian here:
http://www.raspberrypi.org/downloads
I copied the recommended hard-float image on an SD card and the Raspberry Pi boots fine with it.
Then I downloaded the soft-float version of Raspbian because I need it to get some software running that does not work on the hard-float version. I formatted the SD card again, copied the soft-float image onto it and tried to boot the Raspberry Pi with it.
Problem: the Raspbery Pi doesn't boot with the soft-float version of Raspbian!! I see the green "ACT" LED light up for less than a second. After that only the red power LED is on and nothing happens after that.
I repeated this process a couple of times and redownloaded the images, checked the SHA of the downloaded file, etc. It just doesn't work. The hard-float image always boots up (green "ACT" light flashes rapidly like normal).
Any ideas?

Answer 1

Update: If you have a newer Raspberry Pi with Hynix memory then the older versions of Raspbian will not boot. Specifically you'll need at least the 2013-02-09 Debian 7 (Wheezy) build.
See this post.
Now, the 2013-02-09 Wheezy build is a hard-float version, so you can't use that, but you can update the kernel image of your soft-float version which is actually independent of the Linux OS (I'm told that basically the GPU boots the Raspberry Pi, and it runs the ARM as a kind of co-processor). So, you can run rpi-update to update your kernel, and it should be all OK.
There's a bit of a catch-22 if you don't own any of the older Raspberry Pis that will boot the older images--how can you update the OS if the only Raspberry Pi you have is a newer one which won't boot? In your case it sounds like you have access to an older one, so you're OK. For those who don't, maybe someone will eventually post an updated soft-float version, but until then perhaps you can try the following. I haven't; it's just a theory, but at this point you don't have much to lose :-)
Burn the latest Wheezy image (2012-02-09) to an extra SD card
Mount this SD card on Windows
Copy all the files except *gz ones which correspond to the Linux filesystem. Basically, all the boot images and configuration files
Mount the SD card containing your soft-float image and overwrite the boot image files
Hopefully have a beer to celebrate?
Previous post:
Yes, I had this same problem. I don't know exactly what is wrong, but the start_elf image won't boot, at least with the recent set of Raspberry Pis. I can't believe Raspbian would release something that broken, so I suspect it works for some Raspberry Pis, but not others. What you need to do is:
Burn the hard-float copy of Wheezy to an SD card. You're going to snatch off the boot image (which works) and copy it to the soft float one.
Mount the SD card on a Windows machine. The boot partition is FAT, so you'll be able to see it. Look for the file start.elf. Copy it to your Windows machine.
Burn the soft-float copy of Wheezy to an SD card and mount it on the Windows box.
Replace it's start.elf with the copy from your hard-float one.
Crack open a beer and enjoy.
See my related post.

Answer 2

Just image one card with hard-float(Raspbian “wheezy”), and the other
with soft-float(Soft-float Debian “wheezy”). Plug both into a Windows PC and
copy all files (you can see at all) from the hard-float onto the
soft-float card, replacing existing ones.
Explanation: http://www.raspberrypi.org/archives/3534
P.S. You can, of course, copy those files to a temporary folder first,
swap cards and then replace all files on the soft-float card with
those in the temporary folder.
bootcode.bin
start.elf
fixup.dat
From Raspberry Pi SD card with this Soft-float Debian "wheezy" did not want to boot

Answer 3

When you dd the image, make sure bs=1M...
After trying all the things in the other answers, it was finally the way to make it work on a latest Raspberry Pi out of the box. I've actually found this a good help with several Raspberry Pi applications/code.