From: Hollis Blanchard <hollisb@us.ibm.com>
To: kvm-devel@lists.sourceforge.net
Cc: kvm-ppc-devel@lists.sourceforge.net, jyoung5@us.ibm.com,
Jan Kiszka <jan.kiszka@web.de>
Subject: Re: [RFC] Reworking KVM_DEBUG_GUEST
Date: Wed, 14 May 2008 13:25:32 -0500 [thread overview]
Message-ID: <200805141325.32231.hollisb@us.ibm.com> (raw)
In-Reply-To: <482B0533.2060603@web.de>
On Wednesday 14 May 2008 10:28:51 Jan Kiszka wrote:
> So gdb on power relies only on those few hw-breakpoints? With x86 you
> can perfectly run gdb (with soft BPs) in parallel with the gdbstub
> (currently based on hw-BPs, but the same would be true for soft-BPs
> inserted by the gdbstub).
GDB on Power inserts trap instructions, i.e. standard "soft" breakpoints. It
does not rely on the hardware breakpoints.
It gets a little more complicated when you involve a GDB stub. IIRC, GDB will
ask the stub to set the breakpoint, and if the stub doesn't support it, GDB
will fall back to overwriting the instructions in memory. Does the Qemu GDB
stub advertise breakpoint support?
If not, the only support needed in KVM would be to send all debug interrupts
to qemu, and allow qemu to send them back down for in-guest breakpoints.
--
Hollis Blanchard
IBM Linux Technology Center
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next prev parent reply other threads:[~2008-05-14 18:25 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-05-12 11:34 [RFC] Reworking KVM_DEBUG_GUEST Jan Kiszka
2008-05-14 15:12 ` Jerone Young
2008-05-14 15:28 ` Jan Kiszka
2008-05-14 15:55 ` Jerone Young
2008-05-14 18:25 ` Hollis Blanchard [this message]
2008-05-14 19:10 ` Jan Kiszka
2008-05-14 19:33 ` Hollis Blanchard
2008-05-14 19:49 ` Jan Kiszka
2008-05-14 21:06 ` Hollis Blanchard
2008-05-14 21:11 ` [kvm-ppc-devel] " Hollis Blanchard
2008-05-14 21:13 ` Hollis Blanchard
2008-05-15 7:47 ` Avi Kivity
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