From owner-freebsd-alpha  Mon Sep 18 16:38:23 2000
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Date: Mon, 18 Sep 2000 16:38:19 -0700 (PDT)
From: Matthew Jacob <mjacob@feral.com>
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To: John Baldwin <jhb@FreeBSD.org>
Cc: alpha@FreeBSD.org
Subject: RE: cvs commit: src/sys/boot/alpha/common main.c
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This was the same pattern that got me. It's what had convinced me that
libstand was to blame. Gee- I dunno now...


On Mon, 18 Sep 2000, John Baldwin wrote:

> [ moved to -alpha ]
> 
> On 18-Sep-00 Matthew Jacob wrote:
> > 
> >> 
> >> On 18-Sep-00 Matthew Jacob wrote:
> >> > 
> >> > Really?
> >> > 
> >> > Hmm. Thought we got this one for the moment.
> >> > 
> >> > Are you sure you remembered to disklabel -B the new boot1?
> >> 
> >> Yep. :(  I have the ra's from the old loader that used to
> >> work (although I don't have a loader.sym for that) and for
> >> the new loader.  I'll see what I can do with that.
> > 
> > Does i die in loader or in boot1?
> 
> Loader:
> 
> 0x2001cce0 <memcpy>:    mov     a0,v0
> 0x2001cce4 <memcpy+4>:  ble     a2,0x2001cf34 <memcpy+596>
> 0x2001cce8 <memcpy+8>:  subq    a0,a1,t5
> 0x2001ccec <memcpy+12>: cmpult  t5,a2,t5
> 0x2001ccf0 <memcpy+16>: bne     t5,0x2001ce88 <memcpy+424>
> 0x2001ccf4 <memcpy+20>: addq    a1,a2,a3
> 0x2001ccf8 <memcpy+24>: ldq_u   t2,0(a1)
> 0x2001ccfc <memcpy+28>: xor     a1,a0,t0
> 0x2001cd00 <memcpy+32>: and     t0,0x7,t0
> 0x2001cd04 <memcpy+36>: and     a0,0x7,t1
> 0x2001cd08 <memcpy+40>: bne     t0,0x2001cd70 <memcpy+144>
> 0x2001cd0c <memcpy+44>: beq     t1,0x2001cd24 <memcpy+68>
> 0x2001cd10 <memcpy+48>: ldq_u   t3,0(a0)
> 0x2001cd14 <memcpy+52>: addq    a2,t1,a2
> 0x2001cd18 <memcpy+56>: mskqh   t2,a1,t2
> 
> It dies with PC = 0 at that last address
> 
> I guess it is dereferencing a NULL pointer or something silly like
> that?
> 
> Hmm, looking in src/libc/alpha/string/bcopy.S:
> 
>         /* src & dst have same alignment */
>         beq     t1,bcopy_all_aligned
> 
>         ldq_u   t3,0(DSTREG)
>         addq    SIZEREG,t1,SIZEREG
>         mskqh   t2,SRCREG,t2
>         mskql   t3,SRCREG,t3
>         or      t2,t3,t2
> 
> So it looks like possibly a NULL source?
> 
> -- 
> 
> John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/
> "Power Users Use the Power to Serve!"  -  http://www.FreeBSD.org/
> 



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