pvc wrote:
[*]BIOS/MBR stuff stays completely unchanged. BIOS only booting is perfectly valid for x86-64.[/list]
For older hardware, or for VMs. If you can install a valid MBR (not a dummy compatibility one) and boot from Legacy BIOS at all, you can boot into long mode from it.
TL;DR:
BIOS is going away, and mostly has already.
All modern motherboards (by which I mean motherboards made after 2010, and specifically any which can mount an Intel or AMD CPU from around 2012 onwards) use
UEFI firmware - the CPU manufacturers simply stopped supporting the older style of BIOS in their firmware, so it became next to impossible to make a BIOS-only alternative for the Intel and AMD parts.
The UEFI specification does define a way of booting with the Legacy BIOS called the Compatibility Support Module (CSM). This includes support for a bare MBR rather than a GPT. This was an optional feature however, and was only intended to make the transition to UEFI smoother, as it let people install existing operating systems on computers using newer motherboards.
As of this year, newer Intel and AMD firmware won't support CSM, and a most existing motherboards from around 2015 onward have already dropped support for the CSM.
You can still run a BIOS system in a VM, since that can use its own simulated firmware, but for bare metal, you'll be out of luck.
On a more positive (?) note, there's reason to think that Intel will shift entirely to 64-bit as the default and only mode some time in the next few years, so it might not be an issue for later PCs. But then, perhaps Microsoft will talk the PC manufacturers into following Apple's lead, and the monster known as x86 will be slain forever...
Baseless speculation ahoy!
My guess? Apple is going to buy up ARM, or try to since the SEC will surely have something to say about it. I don't know if Apple would stop licensing it or not, but given the goal of this move, it is possible they would. Chances are either way they would want to own ARM so that they won't be beholden to another IP owner.
Alternately, Amazon may preemptively buy ARM, either to keep it for their own server designs or to ensure Apple doesn't hoard it. If they refuse to continue licensing it to Apple, I expect that Apple would - and probably already are - design their own CPUs on a proprietary architecture.
If either of them succeed, and then move to lock out others from the ARM design, PCs will stay as they are for a while longer, but the SBC world will scramble to move to RISC-V, or MIPS, or some similar open-standard CPU architecture.
Either way, SBC manufacturers are not going to want to risk getting their legs cut out from under them, which is why I expect a move to RISC-V if any of this happens. The impact of jumping to RISC-V before there are any efficient core designs available for the architecture is left ans a exercise for the readers.
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