Re: kgdb on amd64

[Patrick Welche <prlw1%cam.ac.uk@localhost>]

On Wed, Jun 24, 2015 at 04:42:12PM +0100, Patrick Welche wrote:
> The reason kgdb wasn't working all this time on amd64 is that GETC()
> returns -1 immediately whether or not a character is available =>
> all of kgdb's checksums fail due to the extra "-1" characters.

The attached gets us that far.
(Next the target suffers a lock panic on receipt of a "m" command)

Cheers,

Patrick

Index: kgdb_stub.c
===================================================================
RCS file: /cvsroot/src/sys/kern/kgdb_stub.c,v
retrieving revision 1.28
diff -u -p -r1.28 kgdb_stub.c
--- kgdb_stub.c	21 Sep 2014 17:17:15 -0000	1.28
+++ kgdb_stub.c	24 Jun 2015 16:37:55 -0000
@@ -244,7 +245,9 @@ kgdb_send(const u_char *bp)
 		PUTC(KGDB_END);
 		PUTC(i2digit(csum >> 4));
 		PUTC(i2digit(csum));
-	} while ((c = GETC() & 0x7f) == KGDB_BADP);
+		while ((c = GETC()) == -1)
+			;
+	} while ((c & 0x7f) == KGDB_BADP);
 }
 
 /*
@@ -261,17 +264,25 @@ kgdb_recv(u_char *bp, int maxlen)
 	do {
 		p = bp;
 		csum = len = 0;
-		while ((c = GETC()) != KGDB_START)
+		do {
+			while ((c = GETC()) == -1)
+				;
 			DPRINTF(("%c",c));
+		} while (c != KGDB_START);
+
 		DPRINTF(("%c Start ",c));
 
-		while ((c = GETC()) != KGDB_END && len < maxlen) {
+		do {
+			while ((c = GETC()) == -1)
+				;
+			if (c == KGDB_END)
+				break;
 			DPRINTF(("%c",c));
 			c &= 0x7f;
 			csum += c;
 			*p++ = c;
 			len++;
-		}
+		} while (len < maxlen);
 		csum &= 0xff;
 		*p = '\0';
 		DPRINTF(("%c End ", c));
@@ -283,10 +294,12 @@ kgdb_recv(u_char *bp, int maxlen)
 		}
 		tmpcsum = csum;
 
-		c = GETC();
+		while ((c = GETC()) == -1)
+			;
 		DPRINTF(("%c",c));
 		csum -= digit2i(c) * 16;
-		c = GETC();
+		while ((c = GETC()) == -1)
+			;
 		DPRINTF(("%c",c));
 		csum -= digit2i(c);
 
@@ -326,7 +339,7 @@ kgdb_attach(int (*getfn)(void *), void (
  * This function does all command processing for interfacing to
  * a remote gdb.  Note that the error codes are ignored by gdb
  * at present, but might eventually become meaningful. (XXX)
- * It might makes sense to use POSIX errno values, because
+ * It might make sense to use POSIX errno values, because
  * that is what the gdb/remote.c functions want to return.
  */
 int