Re: [PATCH v1 08/14] plugins: add qemu_plugin_cb_flags to kernel-doc

["Alex Bennée" <alex.bennee@linaro.org>]

Aaron Lindsay <aaron@os.amperecomputing.com> writes:

> On Mar 12 17:28, Alex Bennée wrote:
>> Also add a note to explain currently they are unused.
>> 
>> Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
>
> I'm personally interested in one clarification below, but don't think
> that affects my:
>
> Reviewed-by: Aaron Lindsay <aaron@os.amperecomputing.com>
>
>> ---
>>  include/qemu/qemu-plugin.h | 16 +++++++++++++---
>>  1 file changed, 13 insertions(+), 3 deletions(-)
>> 
>> diff --git a/include/qemu/qemu-plugin.h b/include/qemu/qemu-plugin.h
>> index 9ae3940d89..c98866a637 100644
>> --- a/include/qemu/qemu-plugin.h
>> +++ b/include/qemu/qemu-plugin.h
>> @@ -207,10 +207,20 @@ struct qemu_plugin_tb;
>>  /** struct qemu_plugin_insn - Opaque handle for a translated instruction */
>>  struct qemu_plugin_insn;
>>  
>> +/**
>> + * enum qemu_plugin_cb_flags - type of callback
>> + *
>> + * @QEMU_PLUGIN_CB_NO_REGS: callback does not access the CPU's regs
>> + * @QEMU_PLUGIN_CB_R_REGS: callback reads the CPU's regs
>> + * @QEMU_PLUGIN_CB_RW_REGS: callback reads and writes the CPU's regs
>> + *
>> + * Note: currently unused, plugins cannot read or change system
>> + * register state.
>
> They are unused in the sense that the current plugin interface does not
> provide a way to make use of them. But are they completely free from
> side effects?

They are free of side effects visible to the plugin. Under the covers it
uses the existing TCG_CALL_NO_* mechanics to ensure that register state
is synced to/from TCG temporaries before the callback.

>
> -Aaron


-- 
Alex Bennée