Date: Sat, 28 Feb 1998 11:43:49 +1030 From: Greg Lehey <grog@lemis.com> To: FreeBSD Hackers <hackers@FreeBSD.ORG> Subject: Kernel debugging: what's going on here? Message-ID: <19980228114349.01329@freebie.lemis.com>
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Can anybody explain this to me? I'm writing a disk block, and am currently at bwrite: (kgdb) bt #0 bwrite (bp=0xf051ec00) at ../../kern/vfs_bio.c:364 #1 0xf0138d6a in vop_stdbwrite (ap=0xf2a76c74) at ../../kern/vfs_default.c:283 #2 0xf0138bb1 in vop_defaultop (ap=0xf2a76c74) at ../../kern/vfs_default.c:130 #3 0xf0146639 in spec_vnoperate (ap=0xf2a76c74) at ../../miscfs/specfs/spec_vnops.c:127 #4 0xf01c5679 in ufs_vnoperatespec (ap=0xf2a76c74) at ../../ufs/ufs/ufs_vnops.c:2242 #5 0xf2aab097 in VOP_BWRITE (bp=0xf051ec00) at vnode_if.h:1117 #6 0xf2aa95c4 in vinumstart (vol=0xf0563000, bp=0xf10f1bb0) at request.c:228 #7 0xf2aa9189 in vinumstrategy (bp=0xf10f1bb0) at request.c:71 #8 0xf2aa7b63 in vinum_writedisklabel (vol=0xf0563000, lp=0xf0563110) at io.c:830 I've handed a buffer header up from frame 6 (not the bp in the parameter list). When it gets to bwrite, it has a different content. gdb tells me different contents depending on the frame it's in: (kgdb) f 0 #0 bwrite (bp=0xf051ec00) at ../../kern/vfs_bio.c:364 364 int oldflags = bp->b_flags; (kgdb) p bp->b_vp $13 = (struct vnode *) 0xf29ecbc0 (kgdb) p ((struct vnode *) 0xf29ecbc0)->v_type $14 = VBLK (kgdb) f 6 #6 0xf2aa95c4 in vinumstart (vol=0xf0563000, bp=0xf10f1bb0) at request.c:228 228 VOP_BWRITE (&rqe->b); /* do an asynchronous write */ (kgdb) p ((struct vnode *) 0xf29ecbc0)->v_type $15 = VNON (kgdb) Significant parts of the vnode are different; I just showed v_type to demonstrate it. What's going on here? I don't see any remapping of memory going on anwhere here. Is this a bug in gdb, or in me? Greg To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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