On 08/12/2013 08:38 PM, Sarah Sharp wrote:
On Mon, Aug 12, 2013 at 01:18:47PM -0400, Steven Rostedt wrote:On Mon, 12 Aug 2013 20:07:29 +0300 Xenia Ragiadakou <burzalodowa@xxxxxxxxx> wrote:Hi, I would like to enable a trace event early so that i can view the debug statements trace generated during usb 3.0 host controller driver initialization. I followed the instruction in Documentation/trace/events.txt: "In order to facilitate early boot debugging, use boot option: trace_event=[event-list] where event-list is a comma separated list of events." and added trace_event=[xhci-hcd:xhci_dbg_init] (where xhci-hcd is the trace system and xhci_dbg_init is the trace event that i want to enable) in the boot parameters but it did not work. More specifically, I added in /etc/grub/default: GRUB_CMDLINE_LINUX="trace_event=[xhci-hcd:xhci_dbg_init]" After updating grub, boot parameters in /boot/grub/grub.cfg were changed into: linux /boot/vmlinuz-3.9.9.130805+ root=UUID=8af1b7fc-76c1-4cab-97ef-78ef5e29e084 ro trace_event=[xhci-hcd:xhci_dbg_init] quiet radeon.audio=1 Do I miss something? Any advice would be appreciated.Hi Ksenia, I'm guessing that xhci-hcd is a module. Currently we do not have a way to enable events on module load. We have talked about implementing this feature, and I believe I even have patches somewhere that do it, but we never pushed it to completion.Yes, xhci-hcd is usually complied as a module. You can compile it in, and some distros chose to do that for performance reasons, but not many. Xenia, I would suggest for now just configuring the driver as built-in, so you can test your code.If you want, I can look for those patches and perhaps they may help you. I think you are the second person to ask for them. I probably should do it regardless ;-)Heh, you should get an OPW intern to complete the patches in the next round. ;) Sarah Sharp
Hi Steven,Even after configuring the kernel with the xhci driver as built-in, i did not manage to enable xgci trace events early, by setting the trace_event boot option. If you ever have time and find this patch, is it possible to send it to me too?
thanks a lot, ksenia -- To unsubscribe from this list: send the line "unsubscribe linux-trace-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
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