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RISC-V Eyeing Mainline In Time For The Linux 4.15 Kernel

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  • RISC-V Eyeing Mainline In Time For The Linux 4.15 Kernel

    Phoronix: RISC-V Eyeing Mainline In Time For The Linux 4.15 Kernel

    RISC-V developers have been preparing their kernel port for the mainline Linux tree while it's looking like for Linux 4.15 that goal may finally be realized...

    http://www.phoronix.com/scan.php?pag...nux-4.15-Plans

  • #2
    Good stuff. :- )

    Now to see some hardware with supervisor (or hypervisor!) mode would be swell.

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    • #3
      I agree it's great stuff, but aren't current chips essentially 300 Mhz 8-bit (extended by a PAE type scheme) microcontrollers? The hardware isn't (right now) exciting.

      But the project is young, the interest high. I'm happy to read this. But it's too soon to tack about virtualization just yet.

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      • #4
        Originally posted by AndyChow View Post
        I agree it's great stuff, but aren't current chips essentially 300 Mhz 8-bit (extended by a PAE type scheme) microcontrollers? The hardware isn't (right now) exciting.

        But the project is young, the interest high. I'm happy to read this. But it's too soon to tack about virtualization just yet.
        There is no RISC-V with less than 32 bits in general purpose registers. But I agree, there aren't really computers with enough memory to run Linux usably yet.

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        • #5
          RISC-V homepage is here: https://riscv.org/

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          • #6
            Originally posted by CrystalGamma View Post
            There is no RISC-V with less than 32 bits in general purpose registers. But I agree, there aren't really computers with enough memory to run Linux usably yet.
            Atheros 9331 is @400mhz is one of the best cheap router SoCs out there for 150Mbps APs. His big brother QCA9531 @650MHz and the MTK 7628NN @580Mhz are common enough for 300Mbps +PPP and RADIUS. Plenty of 5G boxes running just fine at the 500Mhz too. And they're all using linux with LEDE\OpenWrt.

            The RISC-V linux marketspace is huge. Everything MIPS and much of ARM's low-end is basically up for grabs for an ISA that doesn't charge licensing fees. And once Android has good support and heavy silicon catches up, there's not a whole lot stopping RISC-V from entering the smartphone market.

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            • #7
              Originally posted by c117152 View Post
              Atheros 9331 is @400mhz is one of the best cheap router SoCs out there for 150Mbps APs. His big brother QCA9531 @650MHz and the MTK 7628NN @580Mhz are common enough for 300Mbps +PPP and RADIUS. Plenty of 5G boxes running just fine at the 500Mhz too. And they're all using linux with LEDE\OpenWrt.

              The RISC-V linux marketspace is huge. Everything MIPS and much of ARM's low-end is basically up for grabs for an ISA that doesn't charge licensing fees. And once Android has good support and heavy silicon catches up, there's not a whole lot stopping RISC-V from entering the smartphone market.
              Main reason ARM and MIPS sell well is because SoC designers can't be arsed to design their own CPU cores.

              Unless someone makes free RISC-V CPU cores (i.e. spends the resources to design it and then gives it away for free), you'll get similar situations where there will be RISC-V CPU core designs sold with a license.

              Which isn't bad per-se, I mean the company making the CPU core design has any right to ask to get paid for it.

              EDIT:

              What RISC-V allows is that companies designing the CPU cores might opensource the building blocks of their stuff, so making an openhardware CPU will be easier,
              Last edited by starshipeleven; 09-13-2017, 05:08 AM.

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              • #8
                Originally posted by AndyChow View Post
                I agree it's great stuff, but aren't current chips essentially 300 Mhz 8-bit (extended by a PAE type scheme) microcontrollers? The hardware isn't (right now) exciting.

                But the project is young, the interest high. I'm happy to read this. But it's too soon to tack about virtualization just yet.
                No, they're not 8-bit, the HiFive1 is a full 32-bit microcontroller, and runs at 320MHz. The performance is pretty excellent for the segment, probably the best power-performance in an upper-low-end micro. What it lacks is peripherals. At the moment there is no 8-bit (or 16-bit!) RISC-V base ISA, probably because RISC doesn't really function at that size due to register addressing limitations.

                That said, the market (and soon the supply) for much bigger RISC-Vs is huge. I suspect, like c117152, that edge network equipment is an excellent market. Once you get a GPU in there, you start seeing digital signage, kiosks; and maybe Chromebooks on the higher end. Even staying at the microcontroller level, there's a lot of room to make money. Espressif has joined the RISC-V foundation, so you can imagine that they may be shifting from Tensilica to RISC-V for their wifi + microcontroller products. What's lacking in the FE310 is peripherals (specifically on-die audio/control rate ADC/DAC) and maybe main memory size.

                Both Qualcomm and NVIDIA are currently developing products which have RISC-V cores in them (in a sort of deeply integrated embedded controller capacity, for now), Samsung might be as well.

                Also, it's not too soon to talk about virtualization, it's been part of the privileged specification (a version of which is implemented on the FE310 already) since the first version, and is firming up quite quickly, and receiving plenty of research input.
                Last edited by microcode; 09-13-2017, 12:27 PM.

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                • #9
                  Originally posted by microcode View Post
                  At the moment there is no 8-bit (or 16-bit!) RISC-V base ISA, probably because RISC doesn't really function at that size due to register addressing limitations.
                  I wouldn't generalize that far. There is AVR which is 8-bit and RISC. It is used only in small, but popular, microcontrollers.

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                  • #10
                    Purely out of interest, is there any other OS besides Linux that runs on RISC-V?

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