Sunday, 02 August 2015
You might have seen some of the posts I've written in the last few months about adding support in Debian for so-called Mixed-EFI systems like the Intel Bay Trail: a 64-bit processor shipped with a 32-bit EFI implementation.
I've finally seen a public justification from Intel evangelist Brian Richardson as to why these systems are crippled^Wconfigured this way, and it's nice to see our guesses confirmed. The reason is simply cost - like most consumer PCs shipped today, they come with Windows. In terms of system design, it's cheaper to just include the limited memory and storage needed for 32-bit Windows. 64-bit Windows takes a lot more storage in particular. And on modern systems 32-bit Windows can only boot using 32-bit UEFI. Fair enough...
However, Brian goes on to state some more things that are simply out of date, saying that "Linux support for UEFI IA32 is still an unanswered question". Ummm, Brian: we've got working 32-bit x86 UEFI support in our standard Jessie (and newer) installation images already, and they work just fine on CD/DVD or USB stick. We've even gone one stage further than anybody else (thus far!) in adding easy support for running a full 64-bit Linux system on top of those 32-bit UEFI implementations.
I say "thus far" here because all the work here here is Free Software. Other folks added the support in Linux for making a 64-bit kernel work with a 32-bit UEFI; I added code in Linux to expose some of the details to userspace, and code in Grub to work with it. My changes have gone upstream already, so I'd expect to see other distros like Fedora or Ubuntu also using them soon.