Messages in this thread | | | Date | Wed, 14 Jan 2009 10:49:56 +0800 | From | Lai Jiangshan <> | Subject | Re: [PATCH 4/5] ftrace: show ftrace_bprintk()'s formats |
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Jason Baron wrote: > On Wed, Dec 31, 2008 at 10:56:23AM +0800, Lai Jiangshan wrote: >> Impact: let user knows the format >> >> Create a file on <debugfs-dir>/tracing/ to show ftrace_bprintk()'s formats. >> >> This formats will help for these condition: >> 1) User get binary data from core file.(formats are backup before coredump) >> 2) User splice ring_buffer to a file. >> User can use formats for parsing the binary data in userspace. >> > > When I 'cat' trace_bprintk_formats on my system the file is empty. This > seems to be b/c 'ftrace_bprintk' is not being used in this patchset. It > can't be used in patch #5 during marker register b/c the format wouldn't > be known at runtime. Thus, as it currently stands this patch, patch 4/5, > isn't adding much?
If you don't use ftrace_bprintk(), the file trace_bprintk_formats is empty. This file record all formats which ftrace_bprintk() uses.
You can use ftrace_bprintk() everywhere as another printk().
Patch #5 enables binary printk for markers, this is another additional tool for tracing markers.
> > A thought on how this might be resolved would be to have the core marker > code pass us its address so this could be recorded in the trace buffer. > Then, also add some debug file that displays the markers and maps marker > addresses with format strings. >
Patch#5 does it as you said.
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