hi, El Wed, Aug 12, 2009 at 04:25:50AM +1000 Microbit_Ubuntu ha dit:
> On Tue, 2009-08-11 at 13:03 -0400, Robert P. J. Day wrote: > > Kernel and module debugging with gdb: http://cli.gs/LHaA4a. > > The article is quite interesting, however it seems hard to scratch > together relevant (should read : not outdated thus wrong) on debugging > kernel modules on a *remote* target.. > > I've been scouring away for yonks here and I don't seem to be getting > anywhere in a hurry :-( > I've recompiled my target's kernel with remote KGDB enabled, (sysfs et > al for possible manual configuration), full debug on the kernel - just > in case - but trying to pass kernel command argument using kgdbwait > (preceded with kgdboc=ttyS0,115200 eg. or kgdbcon etc) doesn't seem to > get the booting to halt and wait for the gdbmod debugger.... > (I've also tried the sysrq-g break and consorts, no avail either). > > I've had a close look at the kernel/kgdb.c source - added some extra > temp debug messages to try to track code flow and it seems I'm not even > entering these funcs. > > Is there anyone here that can shed some more light on this black magic > cursed trick ? I'm using gdbmod-2.4 btw. > > So, basically : I'm continuing trying to find out if there is a way to > step through kernel module code invoked on a remote (ARM) target by > insmod/modprobe. (gdbmod 2.4 claims it automatically picks up when > module is inserted, but at this stage the kernel just happily boots up > and chugs away, ignoring the wait for remote debugger...?.) > > kgdb's URL has docs (kgdb_docu_full-2.4) but - as per usual - they're > either just plain wrong (eg. the syntax doesn't comply whatsoever with > the Documentation -> Docbook kgdb explained syntax) or others don't seem > to correlate with one another. It seems almost like a 'brute force' test > of all permutations of these various "solutions" is perhaps soon the > only way to remain sane.. :-) > > Googling other resources seems to just bring up unanswered posts on > forums here and there where people seem to be just as confused as I > am :-) > > In short, if anyone drops around here and has done this before (kernel = > 2.6.29.4, using built in remote kgdb), I would love to hear from them to > see if perhaps they've got a suggestion. > I don't mind doing the hard work to learn it properly - but it's always > more enjoyable when one is actually working towards something fruitful > in the end... ! some time ago i had a similar (the same?) problem, trying to debug an ARM device using kgdb. in my case the problem was that the serial port driver (AMBA PL010) lacked the poll_get_char() and poll_put_char() operations, which seem to be necessary for debugging over console. if you happen to use a device with AMBA PL010 try again after applying the patch below. otherwise you might want to check if the driver of your serial port implements the poll functions diff --git a/drivers/serial/amba-pl010.c b/drivers/serial/amba-pl010.c index 58a4879..4b27537 100644 --- a/drivers/serial/amba-pl010.c +++ b/drivers/serial/amba-pl010.c @@ -308,6 +308,32 @@ static void pl010_break_ctl(struct uart_port *port, int break_state) spin_unlock_irqrestore(&uap->port.lock, flags); } +#ifdef CONFIG_CONSOLE_POLL +static int pl010_get_poll_char(struct uart_port *port) +{ + struct uart_amba_port *uap = (struct uart_amba_port *)port; + unsigned int status; + + do { + status = readb(uap->port.membase + UART01x_FR); + } while (!UART_RX_DATA(status)) + + return readb(uap->port.membase + UART01x_DR); +} + +static void pl010_put_poll_char(struct uart_port *port, + unsigned char ch) +{ + struct uart_amba_port *uap = (struct uart_amba_port *)port; + + while (!UART_TX_READY(readb(uap->port.membase + UART01x_FR))) + barrier(); + + writeb(ch, uap->port.membase + UART01x_DR); +} + +#endif /* CONFIG_CONSOLE_POLL */ + static int pl010_startup(struct uart_port *port) { struct uart_amba_port *uap = (struct uart_amba_port *)port; @@ -536,6 +562,10 @@ static struct uart_ops amba_pl010_pops = { .request_port = pl010_request_port, .config_port = pl010_config_port, .verify_port = pl010_verify_port, +#ifdef CONFIG_CONSOLE_POLL + .poll_get_char = pl010_get_poll_char, + .poll_put_char = pl010_put_poll_char, +#endif }; static struct uart_amba_port *amba_ports[UART_NR]; -- Matthias Kaehlcke Embedded Linux Engineer Barcelona Tant qu'il y aura sur terre des hommes pour qui existe un concept d' 'honneur national', la menace d'une nouvelle guerre subsistera (B. Traven) .''`. using free software / Debian GNU/Linux | http://debian.org : :' : `. `'` gpg --keyserver pgp.mit.edu --recv-keys 47D8E5D4 `- -- To unsubscribe from this list: send an email with "unsubscribe kernelnewbies" to [email protected] Please read the FAQ at http://kernelnewbies.org/FAQ
