On Wednesday 08 June 2005 14:34, marco ghidinelli wrote: > hello, > > i've problems debugging a UML SKAS kernel. > the host is an x86 kernel 2.6.12-rc4-skas3-v9-pre4 > the guest is a kernel 2.6.12-rc4. > > GNU gdb 6.3.50.20050606-cvs, > gcc version 3.3.5 (Debian 1:3.3.5-8ubuntu2) > > the problems are: > > 1) a pointer to a struct was not seen by the debugger: > > example session: > > Breakpoint 4, yoghi_init (sch=0x9d1b830, opt=0x9d1b400) > at net/sched/sch_yoghi.c:235 > 235 printk(KERN_DEBUG "Yoghi 0.0.3 Initiaziled\n"); > (gdb) n > Yoghi 0.0.3 Initiaziled > 236 if(q != NULL) > (gdb) n > 237 printk(KERN_DEBUG "yoghi_init: q = > 0x%x\n",(u32)q); > (gdb) n > yoghi_init: q = 0x9d1b480 > 238 return 0; > (gdb) p q > No symbol "q" in current context. > > this is quite annoying but i can get my info in another way: > (gdb) p (struct yoghi_sched_data)*0x9d1b480 Probably the variable was optimized out by the compiler... > 2) sometimes the debugger get lost: > > Breakpoint 3, yoghi_bind (sch=0xa8bcf20, parent=0, classid=176934688) > at net/sched/sch_yoghi.c:271 > 271 return yoghi_get(sch, classid); > (gdb) s > yoghi_get (sch=0x10003, classid=65539) at net/sched/sch_yoghi.c:257 > > note that sch was changed!! > > and sometimes it get completly lost: > > Breakpoint 1, yoghi_get (sch=0x10013, classid=65555) > at net/sched/sch_yoghi.c:259 > 259 u32 band = TC_H_MIN(classid); > (gdb) n > 261 printk(KERN_DEBUG "yoghi_get: classid = %d ; band = %d ; > band2 = %d\n",classid,band,band2); > (gdb) p band > $8 = 19 > (gdb) n > yoghi_get: classid = 65555 ; band = 19 ; band2 = 19 > 262 if (band -1 > q->bands) > (gdb) n > 263 return 0; /* means not found */ > (gdb) n > 265 } > (gdb) n > 0x0a8846d2 in ?? () > (gdb) bt > #0 0x0a8846d2 in ?? () > #1 0x09d1b000 in ?? () > #2 0x00010013 in ?? () > #3 0x00010013 in ?? () > #4 0x00000000 in ?? () > > bye! Sadly gdb is not very reliable, and I can confirm all this is normal... you could try compiling the kernel (or at least the modules of your interest, but you'd better patch the Makefiles) with -O1 instead of -O2...
-- Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!". Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894) http://www.user-mode-linux.org/~blaisorblade ___________________________________ Yahoo! Mail: gratis 1GB per i messaggi e allegati da 10MB http://mail.yahoo.it ------------------------------------------------------- This SF.Net email is sponsored by: NEC IT Guy Games. How far can you shotput a projector? How fast can you ride your desk chair down the office luge track? If you want to score the big prize, get to know the little guy. Play to win an NEC 61" plasma display: http://www.necitguy.com/?r=20 _______________________________________________ User-mode-linux-user mailing list User-mode-linux-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/user-mode-linux-user
