Re: [PATCH 0/3] RISC-V SBI earlycon

Palmer Dabbelt
2018-12-07T18:30:44Z

On Tue, 04 Dec 2018 05:55:04 PST (-0800), anup@brainfault.org wrote:
> This patchset adds RISC-V SBI earlycon and removes RISC-V EARLY_PRINTK.
>
> We should use earlycon over existing EARLY_PRINTK for SBI console because:
> 1. It's a more generic way of implementing early console for debugging
> 2. Current RISC-V EARLY_PRINTK is a compile-time option whereas earlycon
> is enabled at run-time via kernel parameters.
> 3. To use earlycon with SBI, we have to pass "earlycon=sbi" in kernel
> parameters. If earlycon kernel parameter is not provided then kernel
> boots much faster which is very useful in real-world RISC-V deployments.
>
> The patchset is tested on QEMU virt machine. It is based on Linux-4.20-rc5
> and can be found at riscv_earlycon_v1 branch of:
> https://github.com/avpatel/linux.git
>
> Anup Patel (3):
> tty/serial: Add RISC-V SBI earlycon support
> RISC-V: defconfig: Enable RISC-V SBI earlycon support
> RISC-V: Remove EARLY_PRINTK support
>
> arch/riscv/Kconfig.debug | 2 --
> arch/riscv/configs/defconfig | 1 +
> arch/riscv/kernel/setup.c | 28 -------------------------
> drivers/tty/serial/Kconfig | 12 +++++++++++
> drivers/tty/serial/Makefile | 1 +
> drivers/tty/serial/earlycon-riscv-sbi.c | 28 +++++++++++++++++++++++++
> 6 files changed, 42 insertions(+), 30 deletions(-)
> create mode 100644 drivers/tty/serial/earlycon-riscv-sbi.c

I'm adding these to my for-next.

Thanks!