Hi Doug On Mon, Dec 11, 2023 at 10:39 PM Doug Anderson <dianders@xxxxxxxxxxxx> wrote: > > 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: > Yes it's a bug > 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. > The polling driver look for uart and uart8250_core is registered and 4 fake uart are there but there are not still replaced by platform driver that can come later. The try_polling find it but it's the isa-8250 driver. It means that add_uart 8250 is not still happen > 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? > Michael > -Doug -- Michael Nazzareno Trimarchi Co-Founder & Chief Executive Officer M. +39 347 913 2170 michael@xxxxxxxxxxxxxxxxxxxx __________________________________ Amarula Solutions BV Joop Geesinkweg 125, 1114 AB, Amsterdam, NL T. +31 (0)85 111 9172 info@xxxxxxxxxxxxxxxxxxxx www.amarulasolutions.com
