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I just ran the Windows 8 Upgrade Assistant on an older machine (just for fun) and was informed that due to lack of UEFI firmware, Secure Boot would not be supported.

Is it possible for motherboard manufacturers, if they so choose (obviously they won't), to release a firmware flash that would update the BIOS to UEFI (or maybe UEFI+BIOS which some systems have)? Does UEFI require actual hardware support or is it entirely a matter of low-level software?

James T Snell
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Karan
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    I know it won't happen, already mentioned it. But *why* is it not possible? Is it a hardware issue or something else? – Karan Oct 28 '12 at 02:34
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    @Moab and ramhound, it would be interesting to hear _why_ that doesn't work - i.e. the technical reasoning it's incompatible. – nhinkle Oct 28 '12 at 06:28
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    Forgot to link to this earlier. [Here's](http://superuser.com/questions/527080) a motherboard for which Gigabyte released a BIOS to UEFI update. – Karan May 09 '13 at 16:09

3 Answers3

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It's theoretically possible, and may be semi-practical on some computers. What you'd need to do is to merge CoreBoot with a TianoCore UEFI payload. I've never tried it, but I've heard of this being done. Computer manufacturers could of course do this or something similar themselves, although I don't expect many will do so. Aside from the simple technical knowledge required to do this, the major obstacle is one of the size of the EEPROM chips on most motherboards. UEFI is pretty big, and although I don't know the details offhand, my understanding is that it's big enough that motherboard manufacturers wanting to support UEFI have had to increase the size of their EEPROMs to hold UEFI implementations. Thus, such an upgrade would work only on computers that had unusually large EEPROMs to begin with, or on computers on which you could swap out the EEPROM for a bigger one.

Another approach is to put TianoCore UEFI on your hard disk and boot it like a boot loader or OS. This is possible with a TianoCore build called DUET, which I wrote about here. This works only on some computers and is awkward to get running. I also don't know offhand if it supports Secure Boot. Even if it did, Secure Boot on such a configuration would be rather pointless, since it would still rely on a BIOS-mode boot loader to get started, so malware could theoretically still creep in though that unsecured foundation. (OTOH, I'm a bit skeptical that malware would survive the odd journey from BIOS through DUET to a booted OS.)

Rod Smith
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    Thank you for the sole response so far that isn't a wisecrack. I will certainly look into CoreBoot/TianoCore. Also, seems you're right about the only possible hardware limitation being the ROM size. UEFI compatibility seems to be an issue with graphics cards as well, and EVGA for example [plans to release](http://www.evga.com/forums/fb.ashx?m=1779410) a firmware update soon for the GeForce 600 series to add [UEFI GOP](http://en.wikipedia.org/wiki/Unified_Extensible_Firmware_Interface#Graphics_features) support, with the 500 series being left out due to the inadequate BIOS ROM size. – Karan Nov 08 '12 at 19:52
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    Modern systems don't use EEPROMs in the conventional sense. Intel platforms since Nehalem or so have used conventional SPI NOR Flash chips ranging in size from 4MB all the way up to 16MB and larger -- it's flash memory vs. a traditional page-orientated EEPROM. 4MB was the smallest size we ever used on Nehalem platforms, and that barely fit the BIOS + minimal Management Engine firmware. – Krunal Desai Dec 31 '15 at 20:32
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Gigabyte has also done it, for example http://www.gigabyte.co.nl/products/product-page.aspx?pid=3853#bios

Frank
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  • Yes, I mentioned that MB in a [comment above](http://superuser.com/questions/494303/is-is-possible-to-update-bios-to-uefi/786731#comment729410_494303) last year. :) – Karan Sep 05 '14 at 23:39
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It's definitely possible, and has been done.

MSI clickbios.

It's supposed to be a bit buggy, but functional nevertheless.

Milind R
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