On 14/05/15 12:38, Guo, Yejun wrote:
> Thanks Daniel Kurtz and Emil Velikov for the reply.
>
> In general, drm APIs are invoked by user mode drivers, but, I want to mimic
> the behavior of driver in my unit test to create buffer objects. After do
> some searching, I wrote the following code in my unit test (user mode simple
> application based on libdrm). It does work in my old system (cannot go back
> to it and so do not know the exact version), but it failed when porting the
> unit test based on latest libdrm code. I stepped into function drmOpenByName
> and thought it is a typo.
>
> int fd = drmOpen("i915", NULL);
> drm_intel_bufmgr* bufmgr = drm_intel_bufmgr_gem_init(fd, 1024);
> drm_intel_bo * bo = drm_intel_bo_alloc(bufmgr,...);
>
I honestly hope that your code has error checking and you've dropped
them here for simplicity.
> After read the comment, looks like the above code is not used as expected. (I
> execute the utest together with X11 is running).
>
> Back to my original purpose, what's the correct way for me to create bo?
> One possible way is to open("/dev/dri/renderDxxx"), but what should I do if
> the kernel version is too low to has this feature?
>
Afaict there are a few solutions possible (listed in order of preference):
1. Run your test without/outside X
2. Opt for render nodes, but it again depends on exactly what your
program does*.
3. Use open(...cardX...) directly, but you might need to set/drop
master depending your program.
Needless to say personally I would opt for 1 :)
-Emil
* You can confirm with the rest of the Intel crew if your program
requires master/root/auth from the drm and/or i915 module. Alternatively
you can check with the kernel
$ git grep "DRM_AUTH\|DRM_MASTER\|DRM_ROOT_ONLY" --
$(linux_top)/drivers/gpu/drm
