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x86 is already legacy. AMD64 deprecated a bunch of the old stuff, but retained it for backward compatibility. This idea of tweaking x64 with new registers and s

x86 is already legacy. AMD64 deprecated a bunch of the old stuff, but retained it for backward compatibility. This idea of tweaking x64 with new registers and suppressing flag modifications just tells me RISC-V got those things right. But the complexity (circuitry to handle flags) will remain even with this spring cleaning. I'm still waiting for AMD or Intel to make a RISC-V chip that drops in one of their existing sockets. Yeah, you'll need to replace the BIOS and such but I'm looking to buy a new motherboard anyway.

yjftsjthsd-h 3y ago
> I'm still waiting for AMD or Intel to make a RISC-V chip that drops in one of their existing sockets. Yeah, you'll need to replace the BIOS and such but I'm looking to buy a new motherboard anyway. If you need to replace the motherboard, what's the point of reusing the existing socket? That said, I think I've seen this done, although the details are eluding me and web searches aren't helping; I think there was, once upon a time, a motherboard that could swap between x86 and Alpha processors with only minor reconfiguration (like, changing a jumper minor).
- toast0 3y ago
  > I think there was, once upon a time, a motherboard that could swap between x86 and Alpha processors with only minor reconfiguration (like, changing a jumper minor). Deep into rumors that have been circulating in my brain for two decades now... But supposedly Slot A for the (original) K7 Athlon was very similar to the Alpha CPU bus (wikipedia says "The Athlon utilizes the Alpha 21264's EV6 bus architecture with double data rate (DDR) technology.[citation needed]"). The K7 team had some people who had worked on the Alpha at DEC, so there were lots of comparisons drawn.
  - whaleofatw2022 3y ago
    Iirc there was at least a couple samsung alpha boards that used AMDs 750/760. UP1100 and UP1500
- phkahler 3y ago
  >> If you need to replace the motherboard, what's the point of reusing the existing socket? Zero hardware changes for the board maker. I'm not sure it would be possible to reflash from x86 BIOS to RISC-V bios and reboot. That would be cool though. Or maybe they have a jumper to select which is expected (to switch between 2 BIOS images) and everything else is identical.
rbanffy 3y ago
> I'm still waiting for AMD or Intel to make a RISC-V chip that drops in one of their existing sockets There was once a MIPS CPU that was a drop-in replacement for the 80486. It required, of course, a different BIOS. This is one good thing OpenFirmware had going for it.
shash 3y ago
IIRC, Zen at one point had an ARM decode stage. I don't know if it was intended commercially, or they just did it to try out...

yjftsjthsd-h 3y ago

> I'm still waiting for AMD or Intel to make a RISC-V chip that drops in one of their existing sockets. Yeah, you'll need to replace the BIOS and such but I'm looking to buy a new motherboard anyway. If you need to replace the motherboard, what's the point of reusing the existing socket? That said, I think I've seen this done, although the details are eluding me and web searches aren't helping; I think there was, once upon a time, a motherboard that could swap between x86 and Alpha processors with only minor reconfiguration (like, changing a jumper minor).

toast0 3y ago
> I think there was, once upon a time, a motherboard that could swap between x86 and Alpha processors with only minor reconfiguration (like, changing a jumper minor). Deep into rumors that have been circulating in my brain for two decades now... But supposedly Slot A for the (original) K7 Athlon was very similar to the Alpha CPU bus (wikipedia says "The Athlon utilizes the Alpha 21264's EV6 bus architecture with double data rate (DDR) technology.[citation needed]"). The K7 team had some people who had worked on the Alpha at DEC, so there were lots of comparisons drawn.
- whaleofatw2022 3y ago
  Iirc there was at least a couple samsung alpha boards that used AMDs 750/760. UP1100 and UP1500
phkahler 3y ago
>> If you need to replace the motherboard, what's the point of reusing the existing socket? Zero hardware changes for the board maker. I'm not sure it would be possible to reflash from x86 BIOS to RISC-V bios and reboot. That would be cool though. Or maybe they have a jumper to select which is expected (to switch between 2 BIOS images) and everything else is identical.

rbanffy 3y ago

> I'm still waiting for AMD or Intel to make a RISC-V chip that drops in one of their existing sockets There was once a MIPS CPU that was a drop-in replacement for the 80486. It required, of course, a different BIOS. This is one good thing OpenFirmware had going for it.

shash 3y ago

IIRC, Zen at one point had an ARM decode stage. I don't know if it was intended commercially, or they just did it to try out...