serial/sifive: select SERIAL_EARLYCON
Subsystems (5)
PATCH 1/1 serial/sifive: select SERIAL_EARLYCON
The sifive serial driver implements earlycon support, but unless another driver is built in that supports earlycon support it won't be usable. Explicitly select SERIAL_EARLYCON instead.
--- drivers/tty/serial/Kconfig | 1 + 1 file changed, 1 insertion(+)
drivers/tty/serial/Kconfig +1 -0
@@ -1075,6 +1075,7 @@ config SERIAL_SIFIVE_CONSOLE bool "Console on SiFive UART" depends on SERIAL_SIFIVE=y select SERIAL_CORE_CONSOLE + select SERIAL_EARLYCON help Select this option if you would like to use a SiFive UART as the system console.
Signature · 1 line
2.20.1
Quoted 1 line · Christoph Hellwig
The sifive serial driver implements earlycon support,
It should probably be documented in admin-guide/kernel-parameters.txt.
Andreas.
Signature · 3 lines
Andreas Schwab, SUSE Labs, [email protected] GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different."
Quoted 5 lines · Andreas Schwab
Quoted 1 line · Christoph Hellwig
The sifive serial driver implements earlycon support,
It should probably be documented in
admin-guide/kernel-parameters.txt.
How so? Wіth OF and a stdout path you just set earlycon on the command line without any arguments and it will be found.
Quoted 9 lines · Christoph Hellwig
Quoted 5 lines · Andreas Schwab
Quoted 1 line · Christoph Hellwig
The sifive serial driver implements earlycon support,
It should probably be documented in
admin-guide/kernel-parameters.txt.How so? Wіth OF and a stdout path you just set earlycon on the command line without any arguments and it will be found.
Doesn't work for me.
[ 0.000000] Malformed early option 'earlycon'
Andreas.
Signature · 3 lines
Andreas Schwab, SUSE Labs, [email protected] GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different."
Quoted 6 lines · Andreas Schwab
Quoted 2 lines
How so? Wіth OF and a stdout path you just set earlycon on the command line without any arguments and it will be found.
Doesn't work for me.
[ 0.000000] Malformed early option 'earlycon'
That functionality is implemented by param_setup_earlycon and early_init_dt_scan_chosen_stdout. Check why those aren't built into your kernel.
Quoted 11 lines · Christoph Hellwig
Quoted 6 lines · Andreas Schwab
Quoted 2 lines
How so? Wіth OF and a stdout path you just set earlycon on the command line without any arguments and it will be found.
Doesn't work for me.
[ 0.000000] Malformed early option 'earlycon'That functionality is implemented by
param_setup_earlyconandearly_init_dt_scan_chosen_stdout. Check why those aren't built into your kernel.
They are.
Andreas.
Signature · 3 lines
Andreas Schwab, SUSE Labs, [email protected] GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different."
Quoted 11 lines · Christoph Hellwig
Quoted 6 lines · Andreas Schwab
Quoted 2 lines
How so? Wіth OF and a stdout path you just set earlycon on the command line without any arguments and it will be found.
Doesn't work for me.
[ 0.000000] Malformed early option 'earlycon'That functionality is implemented by
param_setup_earlyconandearly_init_dt_scan_chosen_stdout. Check why those aren't built into your kernel.
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.
Quoted 3 lines · Palmer Dabbelt
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.
Quoted 8 lines · Christoph Hellwig
Quoted 3 lines · Palmer Dabbelt
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.
Quoted 6 lines · Palmer Dabbelt
Quoted 5 lines · Christoph Hellwig
Quoted 3 lines · Palmer Dabbelt
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.
Quoted 7 lines
Quoted 3 lines
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.
Andreas.
Signature · 3 lines
Andreas Schwab, SUSE Labs, [email protected] GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different."
Quoted 12 lines · On Mon, 16 Sep 2019 12:40:10 PDT (-0700), [email protected] wrote:
Quoted 10 lines · Palmer Dabbelt
Quoted 8 lines · Christoph Hellwig
Quoted 3 lines · Palmer Dabbelt
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.
Quoted 5 lines
Quoted 3 lines
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
drivers/tty/serial/8250/8250_early.c +1 -0
@@ -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=0x802000
00 -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:
but we don't set it for the HiFive Unleashed. I'd call that a bug, something like this
arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts +1 -0
@@ -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.
Quoted 16 lines · Palmer Dabbelt
but we don't set it for the HiFive Unleashed. I'd call that a bug, something like this
arch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts +1
-0@@ -13,6 +13,7 @@ compatible = "sifive,hifive-unleashed-a00", "sifive,fu540-c000"; chosen { + stdout-path = &uart0; }; cpus {
Quoted 1 line
should fix it. LMK if I've misunderstood something.
If that's how it's supposed to work, ok. Other platforms add it in u-boot.
Andreas.
Signature · 3 lines
Andreas Schwab, SUSE Labs, [email protected] GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different."
Quoted 118 lines · Palmer Dabbelt
Quoted 17 lines · On Mon, 16 Sep 2019 12:40:10 PDT (-0700), [email protected] wrote:
Quoted 15 lines · Palmer Dabbelt
Quoted 12 lines · Christoph Hellwig
Quoted 5 lines · Palmer Dabbelt
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.Quoted 7 lines
Quoted 5 lines
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/riscvfor 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 earlycondrivers/tty/serial/8250/8250_early.c +1
-0@@ -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 MMIO0x10000000(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: probedIf 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:but we don't set it for the HiFive Unleashed. I'd call that a bug, something
like thisarch/riscv/boot/dts/sifive/hifive-unleashed-a00.dts +1
-0@@ -13,6 +13,7 @@ compatible = "sifive,hifive-unleashed-a00", "sifive,fu540- c000"; chosen { + stdout-path = &uart0; };cpus {
Quoted 2 lines
should fix it. LMK if I've misunderstood something.
OpenSBI already adds this node to DT for U-Boot serial console. I have tested that just adding "earlycon" to the commandline works as long as you are using OpenSBI and SERIAL_EARLYCON is enabled.
If this entry can be added to dt residing in kernel, we can remove the code that adds the "stdout-path" from OpenSBI.
Quoted 4 lines
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Signature · 2 lines
Regards, Atish
Quoted 7 lines · Andreas Schwab
Quoted 5 lines · Christoph Hellwig
Quoted 4 lines · Andreas Schwab
Quoted 1 line · Christoph Hellwig
The sifive serial driver implements earlycon support,
Quoted 8 lines
Quoted 4 lines
Quoted 1 line
It should probably be documented in
admin-guide/kernel-parameters.txt.How so? Wіth OF and a stdout path you just set earlycon on the command line without any arguments and it will be found.
Doesn't work for me.
[ 0.000000] Malformed early option 'earlycon'
Try:
earlycon=sifive,0x10010000
If it works, you should see this message on the kernel console very early in the boot:
[ 0.000000] earlycon: sifive0 at MMIO 0x0000000010010000 (options '')
- Paul
Quoted 14 lines · Paul Walmsley
Quoted 12 lines · Andreas Schwab
Quoted 9 lines · Christoph Hellwig
Quoted 5 lines · Andreas Schwab
Quoted 1 line · Christoph Hellwig
The sifive serial driver implements earlycon support,
It should probably be documented in
admin-guide/kernel-parameters.txt.How so? Wіth OF and a stdout path you just set earlycon on the command line without any arguments and it will be found.
Quoted 7 lines
Quoted 3 lines
Doesn't work for me.
[ 0.000000] Malformed early option 'earlycon'Try:
earlycon=sifive,0x10010000
That's not what Christoph wants.
Andreas.
Signature · 3 lines
Andreas Schwab, SUSE Labs, [email protected] GPG Key fingerprint = 0196 BAD8 1CE9 1970 F4BE 1748 E4D4 88E3 0EEA B9D7 "And now for something completely different."
Quoted 5 lines · Andreas Schwab
Quoted 3 lines
Try:
earlycon=sifive,0x10010000That's not what Christoph wants.
Well, what I want is auto selection if the device tree uses the stdout-path. My Kendryte DT uses that and it works like a charm. If it doesn't work for you on the U54 board chances are that your DT doesn't have the right settings and you have to use the line that Paul posted.
Quoted 18 lines · Andreas Schwab
Quoted 16 lines · Paul Walmsley
Quoted 14 lines · Andreas Schwab
Quoted 9 lines · Christoph Hellwig
Quoted 5 lines · Andreas Schwab
Quoted 1 line · Christoph Hellwig
The sifive serial driver implements earlycon support,
It should probably be documented in
admin-guide/kernel-parameters.txt.How so? Wіth OF and a stdout path you just set earlycon on the command line without any arguments and it will be found.
Doesn't work for me.
Quoted 7 lines
Quoted 5 lines
Quoted 1 line
[ 0.000000] Malformed early option 'earlycon'Try:
earlycon=sifive,0x10010000That's not what Christoph wants.
I support Christoph's plan to add generic implicit earlycon support.
In the meantime, once v5.4-rc1 is released, I'll send a patch to add a sifive driver section to the earlycon documentation in admin-guide/kernel-parameters.txt. Thanks for the (earlier) suggestion.
- Paul
Quoted 1 line · Paul Walmsley
I support Christoph's plan to add generic implicit earlycon support.
I'm not planning to add it, it exist already. You just need a DT that sets the stdout node up properly, and a earlycon driver using OF_EARLYCON_DECLARE like the sifive uart driver.
The DT here for example works perfectly fine:
http://git.infradead.org/users/hch/riscv.git/commitdiff/f10e64873eafc68516b8884c06b9290b9887633b
Quoted 5 lines · Christoph Hellwig
The sifive serial driver implements earlycon support, but unless another driver is built in that supports earlycon support it won't be usable. Explicitly select
SERIAL_EARLYCONinstead.Signed-off-by Christoph Hellwig <[email protected]>
- Paul