lowRISC Summer of Code TCP/IP Offload to Minion Cores using Rump Kernels

Sebastian Wicki

Mentored by: Justin Cormack, Antti Kantee Organizer: Alex Bradbury, lowRISC

1 We want an open computing eco-system: comprehensible, flexible and reusable

Operating System Processor Peripherals

2 hardware platform I/O shims & pins lowRISC minion cores RISC-V RISC-V application application ● small, dedicated RISC-V RISC-V RISC-V cores cores minion minion … minion RISC-V cores coherent network I/O network ● specialized for I/O processing L2 cache

● protocols in software

‒e.g. SPI, I2C, SDIO off-chip memory

3 software platform rump kernels

● driver container

‒ file systems, network, audio

● run anywhere

‒ userspace, , bare-metal

‒ integrate into own system

● based on NetBSD

4 project proposal

I/O shims & pins ● rump kernels on RISC-V minion cores application RISC-V RISC-V cores minion … minion ● I/O using rump drivers coherent network I/O network

‒ e.g. TCP/IP L2 cache

● traditional OS on

application cores off-chip memory

5 rump kernels

6 rump kernels: not an

● no processes or application threading

● no system calls management net vfs dev paging signals bt tcp smb ext2 cgd usb vm processes ● no privilege levels ip blk ums

● no handling if kernel

hardware

7 rump kernels: not an operating system

● hypercall interface application

‒ scheduling host process

‒ memory allocation system calls

‒ console output net vfs dev bt tcp smb ext2 cgd usb ‒ I/O hypercalls ip blk ums

if

rump hypercall interface

host platform

8 rump kernels: run anywhere

user space client server

client app client application client rump kernel client clientrump libc libc codeapp code kernelcode hypercall hijack rump kernel

libc rumpclient hypercall hypercall interface

posix posix hardwareposix

● client code is aware of ● unmodified client code ● unmodified client code rump kernel ● intercept libc calls ● rump kernel aware libc ● forward over network

9 rump kernels on minion cores

● hypercalls for bare-metal RISC-V

rump kernel ‒ based on the rumprun unikernel user application ethernet sysproxy ● drivers running on rump server tcp/ip ‒ custom ethernet driver rump hijack I/O libc net ‒ TCP/IPrump stack client from NetBSD ● syscall proxy server hypercall implementation kernel ‒ rewritten to run on bare-metal minion core application core ‒ uses serial line instead of network

10 rump kernels on minion cores

← Request: syscall “send”, data → Request: copyin, data.buf rump kernel ← Response: copyin, data → Response: syscall, retval user application ethernet Ethernet Frame sysproxy send(fd, “GET / HTTP/1.1”, ...) open(“/etc/passwd”) tcp/ip server rump hijack I/O serial libc net rump client syscall open rump_sys_send(fd, …)

hypercall implementation linux kernel

minion core application core

11 Limitations

● currently only runs in Spike

‒ wrote virtual network card

‒ simulates minion core

‒ host offloads into Spike

● system requirements

● everything over serial protocol ‒ use DMA engine for copy{in,out}

● code needs some cleanup

12 Conclusions

● rump kernels are flexible http://rumpkernel.org ‒ not limited to TCP/IP offload @rumpkernel ‒ no need to use syscall proxy #rumpkernel irc.freenode.net ‒ run your own apps on minion cores

● code is reusable Contact: @gandro23

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