Re: remote debugging via FireWire * __fast__ firedump!

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Tue, 4 Dec 2007, Stefan Richter wrote:

A quick note to this text from
http://www.suse.de/~bk/firewire/ohci1394_dma_early.diff :
+	  As all changes to the FireWire bus such as enabling and disabling
+	  devices cause a bus reset and thereby disable remote DMA for all
+	  devices, be sure to have FireWire enabled on the debug host (and
+	  the cable plugged) before booting the debug target for debugging.

Bus resets are also caused by bus managing software, which Linux' old
and new FireWire stacks and the stacks of all other FireWire capable
desktop OSs are to varying degrees.

Yes, I can also trigger it raw1394_reset_bus() from libraw1394.

                                     I wonder if the following could
happen:  The two PCs are directly connected, only the PHY of the
debugging PC is active, then the PHY of the debugged PC is activated,
becomes root node, debugging PC examines the bus, then resets the bus to
force its own PHY to become root node in order to get a working
isochronous resource manager.  This bus reset would switch remote DMA on
the debugged PC off.

Yes, that's the case. The PHY of the debugging PC must be active before the
booting a kernel with the early OHCI-1394 initialisation on the debugged
machine.

I tried to to instruct users to do exactly that in that part of the help
text, but changed the wording now in to hope to make it clearer:

+	  [...] be sure to have the cable plugged and FireWire enabled on
+	  the debugging host before booting the debug target for debugging.

and I added new file, installed as Documentation/debugging-via-ohci1394.txt
to give a more detailed HOWTO with links to all available tools and a step
by step guide on how to create a setup for using firescope.

ftp://ftp.suse.de/private/bk/firewire/kernel/ohci1394_dma_early-v2.diff

I'll submit that patch for full review in my next mail.

Bernhard
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [email protected]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

[Index of Archives]     [Kernel Newbies]     [Netfilter]     [Bugtraq]     [Photo]     [Stuff]     [Gimp]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Video 4 Linux]     [Linux for the blind]     [Linux Resources]
  Powered by Linux