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Re: [Xen-devel] [RESEND] [PATCH] Use GDB 'O' packets for console output

To: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>

From: Tony Breeds <tony@xxxxxxxxxxxxxxxxxx>

Date: Thu, 21 Sep 2006 13:41:28 +1000

Cc: Xen-Devel <xen-devel@xxxxxxxxxxxxxxxxxxx>

Delivery-date: Wed, 20 Sep 2006 20:42:14 -0700

List-id: Xen developer discussion <xen-devel.lists.xensource.com>

Mail-followup-to: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>, Xen-Devel <xen-devel@xxxxxxxxxxxxxxxxxxx>

On Tue, Sep 19, 2006 at 08:27:09AM +0100, Keir Fraser wrote: Hi Kier, Sorry for the delay in my reply. > Sharing a single serial line between console and gdbstub isn't a mode we > particularly considered. It's needed when you only have one functional serial port. > Without something like this patch, I suppose > ordinary console output and gdb packets get mixed together on the line and > confuse the gdb session? Yup. > Does gdb actually print out the console data with > your patch? Sure does. for example: (gdb) target remote | ~/bin/gdb-remote Remote debugging using | ~/bin/gdb-remote __start_xen (mbi=0x74a430) at setup.c:336 336 if (opt_nosmp || ofd_boot_cpu == -1) { (gdb) b domctl.c:getdomaininfo Breakpoint 1 at 0x4020f8: file domctl.c, line 85. (gdb) c Continuing. (XEN) spinning up at most 16 total processors ... ... <snip> xen and dom0 boot output ... Blade4 login: (XEN) Waiting for GDB to attach... Breakpoint 1, getdomaininfo (d=0xa080, info=0xfad8) at domctl.c:85 85 u64 cpu_time = 0; (gdb) > It's not nice to tell core serial code about the debugger. The switch > between raw output and output-via-gdbstub should be entirely in console.c. Attached is a patch that doesn't touch the serial layer at all, and also compiles on x86/ia64. --- From: Tony Breeds <tony@xxxxxxxxxxxxxxxxxx> Use GDB 'O' packets for console output if the serial line is shared and GDB is attached. It may be necessary for gdb and the console to share a serial port. This patch utilises the GDB protocol to encode console output. Feedback greatly appreciated. Signed-off-by: Tony Breeds <tony@xxxxxxxxxxxxxxxxxx> --- Compiled on x86_32/ia64 (with various values of debug= and crash_debug=) Tested on PPC xen/common/gdbstub.c | 26 +++++++++++++++++++++++++- xen/drivers/char/console.c | 27 ++++++++++++++++++++++----- xen/include/asm-ia64/debugger.h | 3 +++ xen/include/asm-powerpc/debugger.h | 3 +++ xen/include/asm-x86/debugger.h | 4 ++++ xen/include/xen/console.h | 3 +++ xen/include/xen/gdbstub.h | 2 ++ 7 files changed, 62 insertions(+), 6 deletions(-) --- diff -r 7a20fed8be73 xen/common/gdbstub.c --- a/xen/common/gdbstub.c Sat Sep 16 09:34:26 2006 -0400 +++ b/xen/common/gdbstub.c Thu Sep 21 13:04:27 2006 +1000 @@ -470,6 +470,28 @@ __gdb_ctx = { }; static struct gdb_context *gdb_ctx = &__gdb_ctx; +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 +582,10 @@ initialise_gdb(void) initialise_gdb(void) { gdb_ctx->serhnd = serial_parse_handle(opt_gdb); - if ( gdb_ctx->serhnd != -1 ) + if ( gdb_ctx->serhnd != -1 ) { + console_enable_debugger_io(gdb_ctx->serhnd); printk("GDB stub initialised.\n"); + } serial_start_sync(gdb_ctx->serhnd); } diff -r 7a20fed8be73 xen/drivers/char/console.c --- a/xen/drivers/char/console.c Sat Sep 16 09:34:26 2006 -0400 +++ b/xen/drivers/char/console.c Thu Sep 21 13:04:27 2006 +1000 @@ -27,6 +27,8 @@ #include <asm/debugger.h> #include <asm/io.h> +/* If a debugger is attached send console output to it */ +static int use_debugger_io = 0; /* console: comma-separated list of console outputs. */ static char opt_console[30] = OPT_CONSOLE_STR; string_param("console", opt_console); @@ -116,6 +118,14 @@ static char serial_rx_ring[SERIAL_RX_SIZ 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 console_enable_debugger_io(int debugger_handle) +{ + if ( debugger_handle != -1 && debugger_handle == sercon_handle ) + use_debugger_io = 1; +} + /* CTRL-<switch_char> switches input direction between Xen and DOM0. */ #define SWITCH_CODE (opt_conswitch[0]-'a'+1) static int xen_rx = 1; /* FALSE => serial input passed to domain 0. */ @@ -191,11 +201,14 @@ static long guest_console_write(XEN_GUES return -EFAULT; kbuf[kcount] = '\0'; - serial_puts(sercon_handle, kbuf); - - for ( kptr = kbuf; *kptr != '\0'; kptr++ ) - vga_putchar(*kptr); - + if ( use_debugger_io && in_debugger() ) + debugger_puts(kbuf); + else { + serial_puts(sercon_handle, kbuf); + + for ( kptr = kbuf; *kptr != '\0'; kptr++ ) + vga_putchar(*kptr); + } guest_handle_add_offset(buffer, kcount); count -= kcount; } @@ -257,6 +270,10 @@ static inline void __putstr(const char * { int c; + if ( use_debugger_io && in_debugger() ) { + debugger_puts(str); + return; + } serial_puts(sercon_handle, str); while ( (c = *str++) != '\0' ) diff -r 7a20fed8be73 xen/include/asm-ia64/debugger.h --- a/xen/include/asm-ia64/debugger.h Sat Sep 16 09:34:26 2006 -0400 +++ b/xen/include/asm-ia64/debugger.h Thu Sep 21 13:04:27 2006 +1000 @@ -111,6 +111,9 @@ static inline int debugger_trap_fatal( } #define debugger_trap_immediate() ((void)0) + +#define debugger_puts(str) ((void)0) +#define in_debugger() (0) #endif #endif // __ASSEMBLLY__ diff -r 7a20fed8be73 xen/include/asm-powerpc/debugger.h --- a/xen/include/asm-powerpc/debugger.h Sat Sep 16 09:34:26 2006 -0400 +++ b/xen/include/asm-powerpc/debugger.h Thu Sep 21 13:04:27 2006 +1000 @@ -54,6 +54,9 @@ static inline void debugger_trap_immedia show_backtrace(sp, lr, lr); } +#define debugger_puts(str) ((void)0) +#define in_debugger() (0) + #endif /* CRASH_DEBUG */ #endif diff -r 7a20fed8be73 xen/include/asm-x86/debugger.h --- a/xen/include/asm-x86/debugger.h Sat Sep 16 09:34:26 2006 -0400 +++ b/xen/include/asm-x86/debugger.h Thu Sep 21 13:04:27 2006 +1000 @@ -102,6 +102,10 @@ static inline int debugger_trap_entry( #define debugger_trap_fatal(v, r) (__debugger_trap_fatal(v, r)) #ifndef debugger_trap_immediate #define debugger_trap_immediate() (__debugger_trap_immediate()) + +#define debugger_puts(str) ((void)0) +#define in_debugger() (0) + #endif #endif /* __X86_DEBUGGER_H__ */ diff -r 7a20fed8be73 xen/include/xen/console.h --- a/xen/include/xen/console.h Sat Sep 16 09:34:26 2006 -0400 +++ b/xen/include/xen/console.h Thu Sep 21 13:04:27 2006 +1000 @@ -26,4 +26,7 @@ void console_start_sync(void); void console_start_sync(void); void console_end_sync(void); +/* Enable debuggger output if the serial console and debugger are on the same + * port */ +void console_enable_debugger_io(int debugger_handle); #endif /* __CONSOLE_H__ */ diff -r 7a20fed8be73 xen/include/xen/gdbstub.h --- a/xen/include/xen/gdbstub.h Sat Sep 16 09:34:26 2006 -0400 +++ b/xen/include/xen/gdbstub.h Thu Sep 21 13:04:27 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 Yours Tony linux.conf.au http://linux.conf.au/ || http://lca2007.linux.org.au/ Jan 15-20 2007 The Australian Linux Technical Conference! _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel

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