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How to understand "?" in probe alias?
- From: Nan Xiao <xiaonan830818 at gmail dot com>
- To: systemtap at sourceware dot org
- Date: Fri, 13 Nov 2015 15:14:02 +0800
- Subject: How to understand "?" in probe alias?
- Authentication-results: sourceware.org; auth=none
Hi all,
Below is "Testing target variable available Example"
(https://sourceware.org/systemtap/SystemTap_Beginners_Guide/targetavailable.html):
probe vm.pagefault = kernel.function("__handle_mm_fault@mm/memory.c") ?,
kernel.function("handle_mm_fault@mm/memory.c") ?
{
name = "pagefault"
write_access = (@defined($flags) ? $flags & FAULT_FLAG_WRITE :
$write_access)
address = $address
}
How to understand "?" in probe alias? After checking Language
reference(https://sourceware.org/systemtap/langref/Components_SystemTap_script.html#SECTION00041000000000000000),
I can't find the explanations of it.
Thanks in advance!
Best Regards
Nan Xiao