[Mesa-dev] [PATCH 2/3] loader: Add an environment variable to override driver name choice.

[Emil Velikov]

On 3 February 2017 at 19:13, Eric Anholt <eric at anholt.net> wrote:
> My vc4 simulator has been implemented so far by having an entrypoint
> claiming to be i965, which was a bit gross.  The simulator would be a lot
> less special if we entered through the vc4 entrypoint like normal, so add
> a loader environment variable to allow the i965 fd to probe as vc4.
> ---
>  src/loader/loader.c | 11 +++++++++++
>  1 file changed, 11 insertions(+)
>
> diff --git a/src/loader/loader.c b/src/loader/loader.c
> index 449ff54d1377..4825151ad5e5 100644
> --- a/src/loader/loader.c
> +++ b/src/loader/loader.c
> @@ -345,6 +345,17 @@ loader_get_driver_for_fd(int fd)
>     int vendor_id, chip_id, i, j;
>     char *driver = NULL;
>
> +   /* Allow an environment variable to force choosing a different driver
> +    * binary.  If that driver binary can't survive on this FD, that's the
> +    * user's problem, but this allows vc4 simulator to run on an i965 host,
> +    * and may be useful for some touch testing of i915 on an i965 host.
> +    */
> +   if (geteuid() == getuid()) {
> +      driver = getenv("MESA_LOADER_DRIVER_OVERRIDE");
Having the override is quite useful even outside the context of vc4.

With this in place we could drop a few other workarounds like

64a005e3eef2e12b11b2837dc7253020bb5c0e60
c3b5afbd4e682f76e16ea85883af571165bd24ee
and perhaps even
91681302d0308a70aece883c3b56a18f9a44041f

We can do that another day, so the series is
Reviewed-by: Emil Velikov <emil.velikov at collabora.com>

Thanks
Emil