Hi, On Fri, Dec 8, 2023 at 1:28 PM Michael Trimarchi <michael@xxxxxxxxxxxxxxxxxxxx> wrote: > > Use late_initcall_sync insted of module init to be sure that > serial driver is really probed and get take handover from > early driver. Awesome that you used the earlycon driver to debug problems with registering the normal driver! :-P > The 8250 register the platform driver after > the 8250 core is initialized. As shown by kdbg > > Thread 2 received signal SIGSEGV, Segmentation fault. > [Switching to Thread 1] > _outb (addr=<optimized out>, value=<optimized out>) at ./include/asm-generic/io.h:584 > 584 __raw_writeb(value, PCI_IOBASE + addr); > (gdb) bt > > This section of the code is too early because in this case > the omap serial is not probed > > Thread 2 received signal SIGSEGV, Segmentation fault. > [Switching to Thread 1] > _outb (addr=<optimized out>, value=<optimized out>) at ./include/asm-generic/io.h:584 > 584 __raw_writeb(value, PCI_IOBASE + addr); > (gdb) bt > > Thread 2 received signal SIGSEGV, Segmentation fault. > [Switching to Thread 1] > _outb (addr=<optimized out>, value=<optimized out>) at ./include/asm-generic/io.h:584 > 584 __raw_writeb(value, PCI_IOBASE + addr); > (gdb) bt > 0 _outb (addr=<optimized out>, value=<optimized out>) at ./include/asm-generic/io.h:584 > 1 logic_outb (value=0 '\000', addr=18446739675637874689) at lib/logic_pio.c:299 > 2 0xffff80008082dfcc in io_serial_out (p=0x0, offset=16760830, value=0) at drivers/tty/serial/8250/8250_port.c:416 > 3 0xffff80008082fe34 in serial_port_out (value=<optimized out>, offset=<optimized out>, up=<optimized out>) > at ./include/linux/serial_core.h:677 > 4 serial8250_do_set_termios (port=0xffff8000828ee940 <serial8250_ports+1568>, termios=0xffff80008292b93c, old=0x0) > at drivers/tty/serial/8250/8250_port.c:2860 > 5 0xffff800080830064 in serial8250_set_termios (port=0xfffffbfffe800000, termios=0xffbffe, old=0x0) > at drivers/tty/serial/8250/8250_port.c:2912 > 6 0xffff80008082571c in uart_set_options (port=0xffff8000828ee940 <serial8250_ports+1568>, co=0x0, baud=115200, parity=110, bits=8, flow=110) > at drivers/tty/serial/serial_core.c:2285 > 7 0xffff800080828434 in uart_poll_init (driver=0xfffffbfffe800000, line=16760830, options=0xffff8000828f7506 <config+6> "115200n8") > at drivers/tty/serial/serial_core.c:2656 > 8 0xffff800080801690 in tty_find_polling_driver (name=0xffff8000828f7500 <config> "ttyS2,115200n8", line=0xffff80008292ba90) > at drivers/tty/tty_io.c:410 > 9 0xffff80008086c0b0 in configure_kgdboc () at drivers/tty/serial/kgdboc.c:194 > 10 0xffff80008086c1ec in kgdboc_probe (pdev=0xfffffbfffe800000) at drivers/tty/serial/kgdboc.c:249 > 11 0xffff8000808b399c in platform_probe (_dev=0xffff000000ebb810) at drivers/base/platform.c:1404 > 12 0xffff8000808b0b44 in call_driver_probe (drv=<optimized out>, dev=<optimized out>) at drivers/base/dd.c:579 > 13 really_probe (dev=0xffff000000ebb810, drv=0xffff80008277f138 <kgdboc_platform_driver+48>) at drivers/base/dd.c:658 > 14 0xffff8000808b0d2c in __driver_probe_device (drv=0xffff80008277f138 <kgdboc_platform_driver+48>, dev=0xffff000000ebb810) > at drivers/base/dd.c:800 > 15 0xffff8000808b0eb8 in driver_probe_device (drv=0xfffffbfffe800000, dev=0xffff000000ebb810) at drivers/base/dd.c:830 > 16 0xffff8000808b0ff4 in __device_attach_driver (drv=0xffff80008277f138 <kgdboc_platform_driver+48>, _data=0xffff80008292bc48) > at drivers/base/dd.c:958 > 17 0xffff8000808ae970 in bus_for_each_drv (bus=0xfffffbfffe800000, start=0x0, data=0xffff80008292bc48, > fn=0xffff8000808b0f3c <__device_attach_driver>) at drivers/base/bus.c:457 > 18 0xffff8000808b1408 in __device_attach (dev=0xffff000000ebb810, allow_async=true) at drivers/base/dd.c:1030 > 19 0xffff8000808b16d8 in device_initial_probe (dev=0xfffffbfffe800000) at drivers/base/dd.c:1079 > 20 0xffff8000808af9f4 in bus_probe_device (dev=0xffff000000ebb810) at drivers/base/bus.c:532 > 21 0xffff8000808ac77c in device_add (dev=0xfffffbfffe800000) at drivers/base/core.c:3625 > 22 0xffff8000808b3428 in platform_device_add (pdev=0xffff000000ebb800) at drivers/base/platform.c:716 > 23 0xffff800081b5dc0c in init_kgdboc () at drivers/tty/serial/kgdboc.c:292 > 24 0xffff800080014db0 in do_one_initcall (fn=0xffff800081b5dba4 <init_kgdboc>) at init/main.c:1236 > 25 0xffff800081b0114c in do_initcall_level (command_line=<optimized out>, level=<optimized out>) at init/main.c:1298 > 26 do_initcalls () at init/main.c:1314 > 27 do_basic_setup () at init/main.c:1333 > 28 kernel_init_freeable () at init/main.c:1551 > 29 0xffff8000810271ec in kernel_init (unused=0xfffffbfffe800000) at init/main.c:1441 > 30 0xffff800080015e80 in ret_from_fork () at arch/arm64/kernel/entry.S:857 > > Signed-off-by: Michael Trimarchi <michael@xxxxxxxxxxxxxxxxxxxx> > --- > drivers/tty/serial/kgdboc.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/tty/serial/kgdboc.c b/drivers/tty/serial/kgdboc.c > index 7ce7bb164005..7f8364507f55 100644 > --- a/drivers/tty/serial/kgdboc.c > +++ b/drivers/tty/serial/kgdboc.c > @@ -622,7 +622,7 @@ console_initcall(kgdboc_earlycon_late_init); > > #endif /* IS_BUILTIN(CONFIG_KGDB_SERIAL_CONSOLE) */ > > -module_init(init_kgdboc); > +late_initcall_sync(init_kgdboc); While I'm not denying that you hit a bug, I don't think this is the correct fix. The way it's supposed to work is: 1. init_kgdboc() runs and registers the singleton kgdb "platform driver". 2. The platform driver's probe function, kgdboc_probe(), runs and checks to see if the console is ready by looking at the return value of configure_kgdboc(). If it's ready then we're good to go. If it's not ready then we defer. So I think the bug here is that somehow the console looks "ready" (because tty_find_polling_driver() can find it) but it isn't actually ready yet (because it crashes). That's what you need to fix. I'll note that, in the past, I've definitely used kgdb on 8250-based UARTs. Is your hardware somehow special or is this a regression? -Doug
