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!
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