diff options
Diffstat (limited to 'docs')
| -rw-r--r-- | docs/tracing.txt | 44 |
1 files changed, 41 insertions, 3 deletions
diff --git a/docs/tracing.txt b/docs/tracing.txt index 3853a6a..3182ee8 100644 --- a/docs/tracing.txt +++ b/docs/tracing.txt @@ -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 @@ -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 |