Can't install Linux on HP laptop - install can't see mSata SSD + HDD combo

Question

I have an HP ENVY TouchSmart Ultrabook 4-1119tu that came with Windows 8.1, and I'm trying to add Debian Jessie in a dual-boot configuration.

PREPARATION

I made space on my hard-drive using a partition utility from Windows 8.1 to shrink the Windows 8.1 partition. Next I created bootable USB media from the Debian ISO I downloaded, and set the UEFI/BIOS settings to boot from USB.

RUNNING DEBIAN JESSIE INSTALLER

Install reported a few devices that required non-free drivers (firmware-realtek and firmware-iwlwifi), but I tracked those down and added them to the USB media.

When I get to the point where the installer is going to partition some or all of the hard drive for linux, only the USB media is listed; the HDD doesn't seem to be getting detected at all.

I'm wondering if that's because this laptop comes with a combination HDD with 32GB SSD (a.k.a. "Intel Smart Response and Rapid Start Technology with 500 GB SATA and a 32GB mSATA")?

This is the point where I get stuck. I've tried switching on Legacy Support in the BIOS setup, but it makes no difference; I get stuck at the same point in the install process.

SIDE NOTE / RANT

There were surprisingly few options in the BIOS setup, and after researching InsydeH20 3.7, it seems that their setup utility has two modes; locked and unlocked. In locked mode a whole bunch of options are hidden. To access the full set of options in unlocked mode, I assumed there would be a secret password or a magic key sequence. Nope.

According to my research, unlocking involves something on the order of a firmware update (and even then, the only options seemed to be some third-party's modded version). I visited both HP's and Insyde's web sites, but no mention of unlocking your BIOS anywhere. I thought I was the owner of this laptop after I paid for it, but apparently I was mistaken. WHAT... THE... HELL?

BACK ON TOPIC

So, I'm out of my depth and out of ideas. Is this just a matter of the installer lacking the right drivers to recognize my HDD, or is this something that can only be accomplished by changing some BIOS option that I can't get access to?

Surely it can't be impossible to install another OS besides Windows on this laptop?

Answer 1

OK, MariusMatutiae pointed me in the right direction. The actual problem was that the Intel Smart Response HDD + SSD combo was set up in a fake RAID configuration. Never occurred to me to look in Windows 8.1 for a way to disable it, but that's where it was (search Apps for keyword 'Intel').