Re: [igt-dev] [PATCH i-g-t] tests/kms_big_fb: Add assert for drm_intel_bufmgr and intel_batchbuffer before usage

Chris Wilson
2019-08-13T10:38:32Z

Quoting Ser, Simon (2019-08-13 11:28:54)
> On Thu, 2019-08-08 at 18:04 +0530, Swati Sharma wrote:
> > if drm_intel_bufmgr_gem_init() or intel_batchbuffer_alloc()
> > returns NULL, it leads to seg fault as below:
> >
> > root@testrunner:/home/testrunner/swati/otc_gen_graphics-intel-gpu-tools#
> > ./tests/kms_big_fb
> > IGT-Version: 1.24-g976db91 (x86_64) (Linux: 5.1.0-rc6+ x86_64)
> > Max driver framebuffer size 8192x8192
> > RAM: 2749 MiB, GPU address space: 134217728 MiB, GGTT mappable size: 256
> > MiB
> > Received signal SIGSEGV.
> > Stack trace:
> > #0 [fatal_sig_handler+0x77]
> > #1 [killpg+0x40]
> > #2 [drm_intel_bo_alloc+0x0]
> > #3 [intel_batchbuffer_reset+0x33]
> > #4 [intel_batchbuffer_alloc+0x34]
> > #5 [__real_main603+0x3e9]
> > #6 [main+0x23]
> > #7 [__libc_start_main+0xf0]
> > #8 [_start+0x29]
> > #9 [<unknown>+0x29]
> > Segmentation fault (core dumped)
> >
> > To prevent this igt_assert() is added for both the functions.
>
> I'm not sure I understand why this segfault happens. Seems like
> drm_intel_bufmgr_gem_init can return NULL in the following cases:
>
> * No compiled with libdrm_intel support, in which case the tests should
> be skipped
> * Allocation failure or pthread mutex failure, which are unlikely to
> happen (but it would be nice to log something when those fail)
> * DRM_IOCTL_I915_GEM_APERTURE fails (but something is printed to
> stderr, it doesn't seem like this is the case here)
>
> Am I missing something?

Usual cause is unrecognised GPU by libdrm. In which case it should be an
igt_require_f(data.bufmgr, "Update libdrm for %s support\n", intel_chipset_get_name(devid))
Roll that up into an <somename>_wrapper and spread far and wide.
(Although I prefer the option of not using libdrm_intel in the first
place.)
-Chris