From mboxrd@z Thu Jan  1 00:00:00 1970
From: Brendan Cully <brendan@cs.ubc.ca>
Subject: Re: help on debugging kernel module in Xen
Date: Fri, 12 Jan 2007 13:41:18 -0800
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On Friday, 12 January 2007 at 16:32, Lily Huang wrote:
> Hi Brendan,
> 
> You are right. After I lift the breakpoint a little bit (to sys_open), the
> breakpoint works.
> 
> But now the domU kept complaining after I did "target remote 127.0.0.1:9999"
> and then "br sys_open":
> 
> /************************************************?
> BUG: soft lockup detected on CPU#0!
> 
> Pid: 0, comm:              swapper
> EIP: 0061:[<c01013a7>] CPU: 0
> EIP is at 0xc01013a7
> EFLAGS: 00000346    Not tainted  (2.6.16.33-xenU #12)
> EAX: 00000000 EBX: 00000001 ECX: 00000000 EDX: 00000000
> ESI: 00000001 EDI: c0354000 EBP: c0355f84 DS: 007b ES: 007b
> CR0: 8005003b CR2: b7f77000 CR3: 1d633000 CR4: 00000640
> [<c0105bb3>] show_trace+0x13/0x20
> [<c0103390>] show_regs+0x190/0x1e0
> [<c013cf48>] softlockup_tick+0x88/0xa0
> [<c0126d45>] do_timer+0x215/0x440
> [<c010858c>] timer_interrupt+0x1bc/0x6a0
> [<c013d09f>] handle_IRQ_event+0x3f/0xd0
> [<c013d1be>] __do_IRQ+0x8e/0xf0
> [<c0106efd>] do_IRQ+0x1d/0x30
> [<c025d2d1>] evtchn_do_upcall+0xa1/0xe0
> [<c0105309>] hypervisor_callback+0x3d/0x48
> [<c01039df>] xen_idle+0x2f/0x60
> [<c0103a82>] cpu_idle+0x72/0xc0
> [<c0102035>] rest_init+0x35/0x40
> [<c035656a>] start_kernel+0x2ea/0x3a0
> [<c010006f>] 0xc010006f
> 
> /********************************************************/
> 
> What's wrong? Looks like I am really doomed to run into so many weird
> problems. :(

soft lockup gets triggered when the kernel hasn't gotten a timer
interrupt in a while. This tends to happen frequently when the kernel
is being debugged. I think there's a kernel config option to turn this
off, or you can just live with the messages.