diff options
Diffstat (limited to 'qemu/docs/tracing.txt')
| -rw-r--r-- | qemu/docs/tracing.txt | 58 |
1 files changed, 48 insertions, 10 deletions
diff --git a/qemu/docs/tracing.txt b/qemu/docs/tracing.txt index 7117c5e7d..0bd6b9cf9 100644 --- a/qemu/docs/tracing.txt +++ b/qemu/docs/tracing.txt @@ -157,9 +157,9 @@ performance penalty. Note that regardless of the selected trace backend, events with the "disable" property will be generated with the "nop" backend. -=== Stderr === +=== Log === -The "stderr" backend sends trace events directly to standard error. This +The "log" backend sends trace events directly to standard error. This effectively turns trace events into debug printfs. This is the simplest backend and can be used together with existing code that @@ -172,9 +172,6 @@ source tree. It may not be as powerful as platform-specific or third-party trace backends but it is portable. This is the recommended trace backend unless you have specific needs for more advanced backends. -The "simple" backend currently does not capture string arguments, it simply -records the char* pointer value instead of the string that is pointed to. - === Ftrace === The "ftrace" backend writes trace data to ftrace marker. This effectively @@ -258,11 +255,11 @@ is generated to make use in scripts more convenient. This step can also be performed manually after a build in order to change the binary name in the .stp probes: - scripts/tracetool --dtrace --stap \ - --binary path/to/qemu-binary \ - --target-type system \ - --target-name x86_64 \ - <trace-events >qemu.stp + scripts/tracetool.py --backends=dtrace --format=stap \ + --binary path/to/qemu-binary \ + --target-type system \ + --target-name x86_64 \ + <trace-events >qemu.stp == Trace event properties == @@ -347,3 +344,44 @@ This will immediately call: and will generate the TCG code to call: void trace_foo(uint8_t a1, uint32_t a2); + +=== "vcpu" === + +Identifies events that trace vCPU-specific information. It implicitly adds a +"CPUState*" argument, and extends the tracing print format to show the vCPU +information. If used together with the "tcg" property, it adds a second +"TCGv_env" argument that must point to the per-target global TCG register that +points to the vCPU when guest code is executed (usually the "cpu_env" variable). + +The following example events: + + foo(uint32_t a) "a=%x" + vcpu bar(uint32_t a) "a=%x" + tcg vcpu baz(uint32_t a) "a=%x", "a=%x" + +Can be used as: + + #include "trace-tcg.h" + + CPUArchState *env; + TCGv_ptr cpu_env; + + void some_disassembly_func(...) + { + /* trace emitted at this point */ + trace_foo(0xd1); + /* trace emitted at this point */ + trace_bar(ENV_GET_CPU(env), 0xd2); + /* trace emitted at this point (env) and when guest code is executed (cpu_env) */ + trace_baz_tcg(ENV_GET_CPU(env), cpu_env, 0xd3); + } + +If the translating vCPU has address 0xc1 and code is later executed by vCPU +0xc2, this would be an example output: + + // at guest code translation + foo a=0xd1 + bar cpu=0xc1 a=0xd2 + baz_trans cpu=0xc1 a=0xd3 + // at guest code execution + baz_exec cpu=0xc2 a=0xd3 |