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    SubjectRe: [PATCH] tty: Don't force RISCV SBI console as preferred console
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    On 4/25/19 6:35 AM, Anup Patel wrote:
    > The Linux kernel will auto-disables all boot consoles whenever it
    > gets a preferred real console.
    >
    > Currently on RISC-V systems, if we have a real console which is not
    > RISCV SBI console then boot consoles (such as earlycon=sbi) are not
    > auto-disabled when a real console (ttyS0 or ttySIF0) is available.
    > This results in duplicate prints at boot-time after kernel starts
    > using real console (i.e. ttyS0 or ttySIF0) if "earlycon=" kernel
    > parameter was passed by bootloader.
    >
    > The reason for above issue is that RISCV SBI console always adds
    > itself as preferred console which is causing other real consoles
    > to be not used as preferred console.
    >

    Do we even need HVC_SBI console to be enabled by default? Disabling
    CONFIG_HVC_RISCV_SBI seems to be fine while running in QEMU.

    If we don't need it, I suggest we should remove the config option from
    defconfig in addition to this patch.

    Regards,
    Atish
    > Ideally "console=" kernel parameter passed by bootloaders should
    > be the one selecting a preferred real console.
    >
    > This patch fixes above issue by not forcing RISCV SBI console as
    > preferred console.
    >
    > Fixes: afa6b1ccfad5 ("tty: New RISC-V SBI console driver")
    > Cc: stable@vger.kernel.org
    > Signed-off-by: Anup Patel <anup.patel@wdc.com>
    > ---
    > drivers/tty/hvc/hvc_riscv_sbi.c | 1 -
    > 1 file changed, 1 deletion(-)
    >
    > diff --git a/drivers/tty/hvc/hvc_riscv_sbi.c b/drivers/tty/hvc/hvc_riscv_sbi.c
    > index 75155bde2b88..31f53fa77e4a 100644
    > --- a/drivers/tty/hvc/hvc_riscv_sbi.c
    > +++ b/drivers/tty/hvc/hvc_riscv_sbi.c
    > @@ -53,7 +53,6 @@ device_initcall(hvc_sbi_init);
    > static int __init hvc_sbi_console_init(void)
    > {
    > hvc_instantiate(0, 0, &hvc_sbi_ops);
    > - add_preferred_console("hvc", 0, NULL);
    >
    > return 0;
    > }
    >

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