QEMU plugins can be loaded via command line arguments or via
the QEMU_PLUGIN environment variable. Currently, only the first method
is documented. Let's document QEMU_PLUGIN.

Signed-off-by: Christoph Muellner <cmuellner@linux.com>
---
 docs/devel/tcg-plugins.rst | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst
index f93ef4fe52..ba48be18d0 100644
--- a/docs/devel/tcg-plugins.rst
+++ b/docs/devel/tcg-plugins.rst
@@ -34,6 +34,10 @@ Arguments are plugin specific and can be used to modify their
 behaviour. In this case the howvec plugin is being asked to use inline
 ops to count and break down the hint instructions by type.
 
+QEMU also evaluates the environment variable ``QEMU_PLUGIN``::
+
+  QEMU_PLUGIN="file=tests/plugin/libhowec.so,inline=on,count=hint" $QEMU
+
 Writing plugins
 ---------------
 
-- 
2.35.1

On Wed, Mar 16, 2022 at 2:40 PM Christoph Muellner <cmuellner@linux.com>
wrote:

> QEMU plugins can be loaded via command line arguments or via
> the QEMU_PLUGIN environment variable. Currently, only the first method
> is documented. Let's document QEMU_PLUGIN.
>
> Signed-off-by: Christoph Muellner <cmuellner@linux.com>
> ---
>  docs/devel/tcg-plugins.rst | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst
> index f93ef4fe52..ba48be18d0 100644
> --- a/docs/devel/tcg-plugins.rst
> +++ b/docs/devel/tcg-plugins.rst
> @@ -34,6 +34,10 @@ Arguments are plugin specific and can be used to modify
> their
>  behaviour. In this case the howvec plugin is being asked to use inline
>  ops to count and break down the hint instructions by type.
>
> +QEMU also evaluates the environment variable ``QEMU_PLUGIN``::
> +
> +  QEMU_PLUGIN="file=tests/plugin/libhowec.so,inline=on,count=hint" $QEMU
>

The plugin howvec is in contrib/plugins, so I think giving the correct path
would be
better. Note also that there's a typo in "libhowec.so".

If you want, you could also fix the next example that has the same path or
leave it
for another patch.

+
>  Writing plugins
>  ---------------
>
> --
> 2.35.1
>
>
Other than that,
Reviewed-By: Mahmoud Mandour <ma.mandourr@gmail.com>

Thanks,
Mahmoud

On Wed, Mar 16, 2022 at 2:44 PM Mahmoud Abumandour <ma.mandourr@gmail.com>
wrote:

>
>
> On Wed, Mar 16, 2022 at 2:40 PM Christoph Muellner <cmuellner@linux.com>
> wrote:
>
>> QEMU plugins can be loaded via command line arguments or via
>> the QEMU_PLUGIN environment variable. Currently, only the first method
>> is documented. Let's document QEMU_PLUGIN.
>>
>> Signed-off-by: Christoph Muellner <cmuellner@linux.com>
>> ---
>>  docs/devel/tcg-plugins.rst | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst
>> index f93ef4fe52..ba48be18d0 100644
>> --- a/docs/devel/tcg-plugins.rst
>> +++ b/docs/devel/tcg-plugins.rst
>> @@ -34,6 +34,10 @@ Arguments are plugin specific and can be used to
>> modify their
>>  behaviour. In this case the howvec plugin is being asked to use inline
>>  ops to count and break down the hint instructions by type.
>>
>> +QEMU also evaluates the environment variable ``QEMU_PLUGIN``::
>> +
>> +  QEMU_PLUGIN="file=tests/plugin/libhowec.so,inline=on,count=hint" $QEMU
>>
>
> The plugin howvec is in contrib/plugins, so I think giving the correct
> path would be
> better. Note also that there's a typo in "libhowec.so".
>

Oh yes, I was just copying the contents of the example above but did not
notice
that this is also wrong.

I'll respin a v2 which fixes the paths.

Thanks!


>
> If you want, you could also fix the next example that has the same path or
> leave it
> for another patch.
>
> +
>>  Writing plugins
>>  ---------------
>>
>> --
>> 2.35.1
>>
>>
> Other than that,
> Reviewed-By: Mahmoud Mandour <ma.mandourr@gmail.com>
>
> Thanks,
> Mahmoud
>

Christoph Muellner <cmuellner@linux.com> writes:

> QEMU plugins can be loaded via command line arguments or via
> the QEMU_PLUGIN environment variable. Currently, only the first method
> is documented. Let's document QEMU_PLUGIN.
>
> Signed-off-by: Christoph Muellner <cmuellner@linux.com>
> ---
>  docs/devel/tcg-plugins.rst | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst
> index f93ef4fe52..ba48be18d0 100644
> --- a/docs/devel/tcg-plugins.rst
> +++ b/docs/devel/tcg-plugins.rst
> @@ -34,6 +34,10 @@ Arguments are plugin specific and can be used to modify their
>  behaviour. In this case the howvec plugin is being asked to use inline
>  ops to count and break down the hint instructions by type.
>  
> +QEMU also evaluates the environment variable ``QEMU_PLUGIN``::

You should also make it clear this only works for *-user builds of QEMU.
For system emulation you still need to use the CLI interface. 

> +
> +  QEMU_PLUGIN="file=tests/plugin/libhowec.so,inline=on,count=hint" $QEMU
> +
>  Writing plugins
>  ---------------


-- 
Alex Bennée

On Wed, Mar 16, 2022 at 4:01 PM Alex Bennée <alex.bennee@linaro.org> wrote:

>
> Christoph Muellner <cmuellner@linux.com> writes:
>
> > QEMU plugins can be loaded via command line arguments or via
> > the QEMU_PLUGIN environment variable. Currently, only the first method
> > is documented. Let's document QEMU_PLUGIN.
> >
> > Signed-off-by: Christoph Muellner <cmuellner@linux.com>
> > ---
> >  docs/devel/tcg-plugins.rst | 4 ++++
> >  1 file changed, 4 insertions(+)
> >
> > diff --git a/docs/devel/tcg-plugins.rst b/docs/devel/tcg-plugins.rst
> > index f93ef4fe52..ba48be18d0 100644
> > --- a/docs/devel/tcg-plugins.rst
> > +++ b/docs/devel/tcg-plugins.rst
> > @@ -34,6 +34,10 @@ Arguments are plugin specific and can be used to
> modify their
> >  behaviour. In this case the howvec plugin is being asked to use inline
> >  ops to count and break down the hint instructions by type.
> >
> > +QEMU also evaluates the environment variable ``QEMU_PLUGIN``::
>
> You should also make it clear this only works for *-user builds of QEMU.
> For system emulation you still need to use the CLI interface.


Looks like this is even more restrictive as I can see support only in
linux-user/main.c.
I'll reword this to only be available for Linux user-mode emulation.

Thanks!


>
>
> > +
> > +  QEMU_PLUGIN="file=tests/plugin/libhowec.so,inline=on,count=hint" $QEMU
> > +
> >  Writing plugins
> >  ---------------
>
>
> --
> Alex Bennée
>