Re: [XenPPC] [RFC] GDB "O" packets

[Hollis Blanchard <hollisb@xxxxxxxxxx>]

I don't particularly like "serial_maybe_add_flags", but I think this is
worth posting to xen-devel to get Keir's feedback.

-- 
Hollis Blanchard
IBM Linux Technology Center

On Fri, 2006-09-01 at 13:54 +1000, Tony Breeds wrote:
> Okay Take 2.
> 
> This patch is a little more invasive than my original approach.  It adds
> a new SERHND flag for debugger output.  With this version any data
> written to the console of dom0 or xen will get sent to the attached GDB
> process.  When gdb detaches console output goes back to the serial
> console.
> 
> Feedback most welcome.
> ---
>  common/gdbstub.c               |   28 +++++++++++++++++++++++++++-
>  drivers/char/console.c         |   11 +++++++++++
>  drivers/char/serial.c          |    5 +++++
>  include/asm-powerpc/debugger.h |    3 +++
>  include/xen/gdbstub.h          |    2 ++
>  include/xen/serial.h           |    5 +++++
>  6 files changed, 53 insertions(+), 1 deletion(-)
> ---
> diff -r 9c4858991254 xen/common/gdbstub.c
> --- a/xen/common/gdbstub.c    Tue Aug 29 07:07:57 2006 -0400
> +++ b/xen/common/gdbstub.c    Fri Sep 01 13:40:19 2006 +1000
> @@ -470,6 +470,30 @@ __gdb_ctx = {
>  };
>  static struct gdb_context *gdb_ctx = &__gdb_ctx;
>  
> +/* FIXME: does this need to be protected by a lock?
> + *        Can it clobber another packet? */
> +void
> +debugger_puts(const char *str)
> +{
> +    char *p;
> +
> +    gdb_start_packet(gdb_ctx);
> +    gdb_write_to_packet_char('O', gdb_ctx);
> +
> +    for(p=(char *)str; *p != '\x0'; p++) {
> +        gdb_write_to_packet_char(hex2char((*p>>4) & 0x0f), gdb_ctx );
> +        gdb_write_to_packet_char(hex2char((*p) & 0x0f), gdb_ctx );
> +    }
> +
> +    gdb_send_packet(gdb_ctx);
> +}
> +
> +int
> +in_debugger(void)
> +{
> +    return gdb_ctx->currently_attached;
> +}
> +
>  /* trap handler: main entry point */
>  int 
>  __trap_to_gdb(struct cpu_user_regs *regs, unsigned long cookie)
> @@ -560,8 +584,10 @@ initialise_gdb(void)
>  initialise_gdb(void)
>  {
>      gdb_ctx->serhnd = serial_parse_handle(opt_gdb);
> -    if ( gdb_ctx->serhnd != -1 )
> +    if ( gdb_ctx->serhnd != -1 ) {
> +        serial_maybe_add_flags(gdb_ctx->serhnd, SERHND_DEBUGGER);
>          printk("GDB stub initialised.\n");
> +    }
>      serial_start_sync(gdb_ctx->serhnd);
>  }
>  
> diff -r 9c4858991254 xen/drivers/char/console.c
> --- a/xen/drivers/char/console.c      Tue Aug 29 07:07:57 2006 -0400
> +++ b/xen/drivers/char/console.c      Fri Sep 01 13:40:19 2006 +1000
> @@ -115,6 +115,17 @@ long read_console_ring(XEN_GUEST_HANDLE(
>  #define SERIAL_RX_MASK(_i) ((_i)&(SERIAL_RX_SIZE-1))
>  static char serial_rx_ring[SERIAL_RX_SIZE];
>  static unsigned int serial_rx_cons, serial_rx_prod;
> +
> +/* Enable debugger output on the serial console if it's the same
> + * port as the debugger */
> +void serial_maybe_add_flags(int debugger_handle, int flags)
> +{
> +    /* If the debugger and the serial console differ only in
> +     * whether SERHND_DEBUGGER is enabled, enable it for the console */
> +    if ( (debugger_handle != -1 ) &&
> +         (debugger_handle & ~flags) == sercon_handle )
> +            sercon_handle |= flags;
> +}
>  
>  /* CTRL-<switch_char> switches input direction between Xen and DOM0. */
>  #define SWITCH_CODE (opt_conswitch[0]-'a'+1)
> diff -r 9c4858991254 xen/drivers/char/serial.c
> --- a/xen/drivers/char/serial.c       Tue Aug 29 07:07:57 2006 -0400
> +++ b/xen/drivers/char/serial.c       Fri Sep 01 13:40:19 2006 +1000
> @@ -14,6 +14,7 @@
>  #include <xen/sched.h>
>  #include <xen/mm.h>
>  #include <xen/serial.h>
> +#include <asm/debugger.h>  /* in_debugger() and debugger_puts() */
>  
>  static struct serial_port com[2] = {
>      { .rx_lock = SPIN_LOCK_UNLOCKED, .tx_lock = SPIN_LOCK_UNLOCKED }, 
> @@ -153,6 +154,10 @@ void serial_puts(int handle, const char 
>  
>      if ( (handle == -1) || !port->driver || !port->driver->putc )
>          return;
> +    if ( (handle & SERHND_DEBUGGER) && in_debugger() ) {
> +        debugger_puts(s);
> +        return;
> +    }
>  
>      spin_lock_irqsave(&port->tx_lock, flags);
>  
> diff -r 9c4858991254 xen/include/asm-powerpc/debugger.h
> --- a/xen/include/asm-powerpc/debugger.h      Tue Aug 29 07:07:57 2006 -0400
> +++ b/xen/include/asm-powerpc/debugger.h      Fri Sep 01 13:40:19 2006 +1000
> @@ -39,6 +39,9 @@ static inline int debugger_trap_fatal(
>  #define debugger_trap_fatal(_v, _r) (0)
>  #define debugger_trap_immediate() ((void)0)
>  
> +#define debugger_puts(str)    ((void)0)
> +#define in_debugger()   (0)
> +
>  #endif /* CRASH_DEBUG */
>  
>  #endif
> diff -r 9c4858991254 xen/include/xen/gdbstub.h
> --- a/xen/include/xen/gdbstub.h       Tue Aug 29 07:07:57 2006 -0400
> +++ b/xen/include/xen/gdbstub.h       Fri Sep 01 13:40:19 2006 +1000
> @@ -90,6 +90,8 @@ void gdb_arch_exit(struct cpu_user_regs 
>  #define SIGTERM         15
>  
>  void initialise_gdb(void);
> +void debugger_puts(const char *str);
> +int in_debugger(void);
>  
>  #else
>  
> diff -r 9c4858991254 xen/include/xen/serial.h
> --- a/xen/include/xen/serial.h        Tue Aug 29 07:07:57 2006 -0400
> +++ b/xen/include/xen/serial.h        Fri Sep 01 13:40:19 2006 +1000
> @@ -66,6 +66,7 @@ struct uart_driver {
>  #define SERHND_HI       (1<<1) /* Mux/demux each transferred char by MSB. */
>  #define SERHND_LO       (1<<2) /* Ditto, except that the MSB is cleared.  */
>  #define SERHND_COOKED   (1<<3) /* Newline/carriage-return translation?    */
> +#define SERHND_DEBUGGER (1<<4) /* Translate console messages for the 
> debugger */
>  
>  /* Two-stage initialisation (before/after IRQ-subsystem initialisation). */
>  void serial_init_preirq(void);
> @@ -132,6 +133,10 @@ void ns16550_init(int index, struct ns16
>  /* Baud rate was pre-configured before invoking the UART driver. */
>  #define BAUD_AUTO (-1)
>  
> +/* Enable debuggger output if the serial console and debugger are on the 
> same 
> + * port */
> +void serial_maybe_add_flags(int debugger_handle, int flags);
> +
>  #endif /* __XEN_SERIAL_H__ */
>  
>  /*
> 
> 
> Yours Tony
> 
>    linux.conf.au       http://linux.conf.au/ || http://lca2007.linux.org.au/
>    Jan 15-20 2007      The Australian Linux Technical Conference!
> 
> 
> _______________________________________________
> Xen-ppc-devel mailing list
> Xen-ppc-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-ppc-devel


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