On Mon, 16 Sep 2019 12:40:10 PDT (-0700), schwab@xxxxxxx wrote:
On Sep 16 2019, Palmer Dabbelt <palmer@xxxxxxxxxx> wrote:
On Sun, 15 Sep 2019 23:42:53 PDT (-0700), Christoph Hellwig wrote:
On Fri, Sep 13, 2019 at 01:40:27PM -0700, Palmer Dabbelt wrote:
OpenEmbedded passes "earlycon=sbi", which I can find in the doumentation.
I can't find anything about just "earlycon". I've sent a patch adding sbi
to the list of earlycon arguments.
earlycon without arguments is documented, although just for ARM64.
I can send a patch to update it to properly cover all DT platforms
in addition.
Thanks. I've kind of lost track of the thread, but assuming that does the
"automatically pick an earlycon" stuff then that's probably what we should
be using in the distros.
Except that it doesn't work.
Sorry, once again I've lost track of the thread.
The code looks generic. The device tree in arch/riscv for the HiFive Unleashed
doesn't have a stdout-path set, which if I understand correctly is used by the
automatic earlycon stuff to pick a console. I gave this a quick test on QEMU,
which finds a 16550 earlycon for me. I use openembedded's qemuriscv64 target,
the following diff to make sure I'm getting an earlycon
diff --git a/drivers/tty/serial/8250/8250_early.c b/drivers/tty/serial/8250/8250_early.c
index 5cd8c36c8fcc..61290714bbcb 100644
--- a/drivers/tty/serial/8250/8250_early.c
+++ b/drivers/tty/serial/8250/8250_early.c
@@ -106,6 +106,7 @@ static void early_serial8250_write(struct console *console,
struct earlycon_device *device = console->data;
struct uart_port *port = &device->port;
+ uart_console_write(port, "_e_", 3, serial_putc);
uart_console_write(port, s, count, serial_putc);
}
and run this command line
/home/palmer/work/linux/openembedded-riscv64/build/tmp-glibc/work/x86_64-linux/qemu-helper-native/1.0-r1/recipe-sysroot-native/usr/bin/qemu-system-riscv64 -device virtio-net-device,netdev=net0,mac=52:54:00:12:35:02 -netdev user,id=net0,hostfwd=tcp::2222-:22,hostfwd=tcp::2323-:23,tftp=/home/palmer/work/linux/openembedded-riscv64/build/tmp-glibc/deploy/images/qemuriscv64 -drive id=disk0,file=/home/palmer/work/linux/openembedded-riscv64/build/tmp-glibc/deploy/images/qemuriscv64/core-image-full-cmdline-qemuriscv64-20190711162644.rootfs.ext4,if=none,format=raw -device virtio-blk-device,drive=disk0 -object rng-random,filename=/dev/urandom,id=rng0 -device virtio-rng-device,rng=rng0 -show-cursor -monitor null -device loader,file=/home/palmer/work/linux/linux/arch/riscv/boot/Image,addr=0x80200000 -nographic -machine virt -m 512 -serial mon:stdio -serial null -kernel /home/palmer/work/linux/openembedded-riscv64/build/tmp-glibc/deploy/images/qemuriscv64/fw_jump.elf -append 'root=/dev/vda rw highres=off console=ttyS0 mem=512M ip=dhcp earlycon '
which gives me some early stuff and then some non-early stuff
_e_[ 0.407579] printk: console [ttyS0] disabled
_e_[ 0.409205] 10000000.uart: ttyS0 at MMIO 0x10000000 (irq = 10, base_baud = 230400) is a 16550A
[ 0.410720] printk: console [ttyS0] enabled
_e_[ 0.410720] printk: console [ttyS0] enabled
[ 0.411391] printk: bootconsole [ns16550a0] disabled
_e_[ 0.411391] printk: bootconsole [ns16550a0] disabled
[ 0.420664] [drm] radeon kernel modesetting enabled.
[ 0.428086] random: fast init done
[ 0.429331] random: crng init done
[ 0.440678] loop: module loaded
[ 0.447607] virtio_blk virtio1: [vda] 262830 512-byte logical blocks (135 MB/128 MiB)
[ 0.469483] libphy: Fixed MDIO Bus: probed
If you don't have something like "/chosen/stdout-path = &uart0;" in your device
tree, then that's probably the issue. Here's where it's set in Christoph's
k210:
http://git.infradead.org/users/hch/riscv.git/blob/f10e64873eafc68516b8884c06b9290b9887633b:/arch/riscv/boot/dts/kendryte/kd210.dts#l20
but we don't set it for the HiFive Unleashed. I'd call that a bug, something
like this
diff --git a/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts b/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts
index 93d68cbd64fe..6d0ec76d93fe 100644
--- a/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts
+++ b/arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts
@@ -13,6 +13,7 @@
compatible = "sifive,hifive-unleashed-a00", "sifive,fu540-c000";
chosen {
+ stdout-path = &uart0;
};
cpus {
should fix it. LMK if I've misunderstood something.
