On Thu, Aug 5, 2021 at 4:47 PM Christian König <christian.koenig@xxxxxxx> wrote:
>
> Am 05.08.21 um 16:07 schrieb Daniel Vetter:
> > On Thu, Aug 5, 2021 at 3:44 PM Christian König <christian.koenig@xxxxxxx> wrote:
> >> Am 05.08.21 um 12:46 schrieb Daniel Vetter:
> >>> This is a very confusingly named function, because not just does it
> >>> init an object, it arms it and provides a point of no return for
> >>> pushing a job into the scheduler. It would be nice if that's a bit
> >>> clearer in the interface.
> >>>
> >>> But the real reason is that I want to push the dependency tracking
> >>> helpers into the scheduler code, and that means drm_sched_job_init
> >>> must be called a lot earlier, without arming the job.
> >>>
> >>> v2:
> >>> - don't change .gitignore (Steven)
> >>> - don't forget v3d (Emma)
> >>>
> >>> v3: Emma noticed that I leak the memory allocated in
> >>> drm_sched_job_init if we bail out before the point of no return in
> >>> subsequent driver patches. To be able to fix this change
> >>> drm_sched_job_cleanup() so it can handle being called both before and
> >>> after drm_sched_job_arm().
> >>>
> >>> Also improve the kerneldoc for this.
> >>>
> >>> v4:
> >>> - Fix the drm_sched_job_cleanup logic, I inverted the booleans, as
> >>> usual (Melissa)
> >>>
> >>> - Christian pointed out that drm_sched_entity_select_rq() also needs
> >>> to be moved into drm_sched_job_arm, which made me realize that the
> >>> job->id definitely needs to be moved too.
> >>>
> >>> Shuffle things to fit between job_init and job_arm.
> >>>
> >>> v5:
> >>> Reshuffle the split between init/arm once more, amdgpu abuses
> >>> drm_sched.ready to signal gpu reset failures. Also document this
> >>> somewhat. (Christian)
> >>>
> >>> v6:
> >>> Rebase on top of the msm drm/sched support. Note that the
> >>> drm_sched_job_init() call is completely misplaced, and hence also the
> >>> split-out drm_sched_entity_push_job(). I've put in a FIXME which the next
> >>> patch will address.
> >>>
> >>> Acked-by: Melissa Wen <mwen@xxxxxxxxxx>
> >>> Cc: Melissa Wen <melissa.srw@xxxxxxxxx>
> >>> Acked-by: Emma Anholt <emma@xxxxxxxxxx>
> >>> Acked-by: Steven Price <steven.price@xxxxxxx> (v2)
> >>> Reviewed-by: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx> (v5)
> >>> Signed-off-by: Daniel Vetter <daniel.vetter@xxxxxxxxx>
> >> At least the amdgpu parts look ok of hand, but I can't judge the rest I
> >> think.
> > The thing that really scares me here and that I got wrong a few times
> > is the cleanup for drm_sched_job at the various points. Can you give
> > those parts in drm/scheduler/ a full review pls, just to make sure? I
> > can note that in the tag ofc, just like a bit more confidence here
> > that it's not busted :-)
>
> I can take another look, but I won't have time for that in the next two
> weeks - vacation and kid starting school.
Hm ok I'll ask others, since this is kinda needed for the msm fix. At
least the msm design relies on this split being present, so fixing it
without this split here would be a pile of rather pointless work.
-Daniel
> Christian.
>
> >
> >> So only Acked-by: Christian König <christian.koenig@xxxxxxx>
> > Thanks, Daniel
> >
> >>> Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
> >>> Cc: Russell King <linux+etnaviv@xxxxxxxxxxxxxxx>
> >>> Cc: Christian Gmeiner <christian.gmeiner@xxxxxxxxx>
> >>> Cc: Qiang Yu <yuq825@xxxxxxxxx>
> >>> Cc: Rob Herring <robh@xxxxxxxxxx>
> >>> Cc: Tomeu Vizoso <tomeu.vizoso@xxxxxxxxxxxxx>
> >>> Cc: Steven Price <steven.price@xxxxxxx>
> >>> Cc: Alyssa Rosenzweig <alyssa.rosenzweig@xxxxxxxxxxxxx>
> >>> Cc: David Airlie <airlied@xxxxxxxx>
> >>> Cc: Daniel Vetter <daniel@xxxxxxxx>
> >>> Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
> >>> Cc: "Christian König" <christian.koenig@xxxxxxx>
> >>> Cc: Masahiro Yamada <masahiroy@xxxxxxxxxx>
> >>> Cc: Kees Cook <keescook@xxxxxxxxxxxx>
> >>> Cc: Adam Borowski <kilobyte@xxxxxxxxxx>
> >>> Cc: Nick Terrell <terrelln@xxxxxx>
> >>> Cc: Mauro Carvalho Chehab <mchehab+huawei@xxxxxxxxxx>
> >>> Cc: Paul Menzel <pmenzel@xxxxxxxxxxxxx>
> >>> Cc: Sami Tolvanen <samitolvanen@xxxxxxxxxx>
> >>> Cc: Viresh Kumar <viresh.kumar@xxxxxxxxxx>
> >>> Cc: Alex Deucher <alexander.deucher@xxxxxxx>
> >>> Cc: Dave Airlie <airlied@xxxxxxxxxx>
> >>> Cc: Nirmoy Das <nirmoy.das@xxxxxxx>
> >>> Cc: Deepak R Varma <mh12gx2825@xxxxxxxxx>
> >>> Cc: Lee Jones <lee.jones@xxxxxxxxxx>
> >>> Cc: Kevin Wang <kevin1.wang@xxxxxxx>
> >>> Cc: Chen Li <chenli@xxxxxxxxxxxxx>
> >>> Cc: Luben Tuikov <luben.tuikov@xxxxxxx>
> >>> Cc: "Marek Olšák" <marek.olsak@xxxxxxx>
> >>> Cc: Dennis Li <Dennis.Li@xxxxxxx>
> >>> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
> >>> Cc: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
> >>> Cc: Sonny Jiang <sonny.jiang@xxxxxxx>
> >>> Cc: Boris Brezillon <boris.brezillon@xxxxxxxxxxxxx>
> >>> Cc: Tian Tao <tiantao6@xxxxxxxxxxxxx>
> >>> Cc: etnaviv@xxxxxxxxxxxxxxxxxxxxx
> >>> Cc: lima@xxxxxxxxxxxxxxxxxxxxx
> >>> Cc: linux-media@xxxxxxxxxxxxxxx
> >>> Cc: linaro-mm-sig@xxxxxxxxxxxxxxxx
> >>> Cc: Emma Anholt <emma@xxxxxxxxxx>
> >>> Cc: Rob Clark <robdclark@xxxxxxxxx>
> >>> Cc: Sean Paul <sean@xxxxxxxxxx>
> >>> Cc: linux-arm-msm@xxxxxxxxxxxxxxx
> >>> Cc: freedreno@xxxxxxxxxxxxxxxxxxxxx
> >>> ---
> >>> drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 2 +
> >>> drivers/gpu/drm/amd/amdgpu/amdgpu_job.c | 2 +
> >>> drivers/gpu/drm/etnaviv/etnaviv_sched.c | 2 +
> >>> drivers/gpu/drm/lima/lima_sched.c | 2 +
> >>> drivers/gpu/drm/msm/msm_gem_submit.c | 3 ++
> >>> drivers/gpu/drm/panfrost/panfrost_job.c | 2 +
> >>> drivers/gpu/drm/scheduler/sched_entity.c | 6 +--
> >>> drivers/gpu/drm/scheduler/sched_fence.c | 19 ++++---
> >>> drivers/gpu/drm/scheduler/sched_main.c | 69 ++++++++++++++++++++----
> >>> drivers/gpu/drm/v3d/v3d_gem.c | 2 +
> >>> include/drm/gpu_scheduler.h | 7 ++-
> >>> 11 files changed, 94 insertions(+), 22 deletions(-)
> >>>
> >>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> >>> index 139cd3bf1ad6..32e80bc6af22 100644
> >>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> >>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
> >>> @@ -1226,6 +1226,8 @@ static int amdgpu_cs_submit(struct amdgpu_cs_parser *p,
> >>> if (r)
> >>> goto error_unlock;
> >>>
> >>> + drm_sched_job_arm(&job->base);
> >>> +
> >>> /* No memory allocation is allowed while holding the notifier lock.
> >>> * The lock is held until amdgpu_cs_submit is finished and fence is
> >>> * added to BOs.
> >>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> >>> index d33e6d97cc89..5ddb955d2315 100644
> >>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> >>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_job.c
> >>> @@ -170,6 +170,8 @@ int amdgpu_job_submit(struct amdgpu_job *job, struct drm_sched_entity *entity,
> >>> if (r)
> >>> return r;
> >>>
> >>> + drm_sched_job_arm(&job->base);
> >>> +
> >>> *f = dma_fence_get(&job->base.s_fence->finished);
> >>> amdgpu_job_free_resources(job);
> >>> drm_sched_entity_push_job(&job->base, entity);
> >>> diff --git a/drivers/gpu/drm/etnaviv/etnaviv_sched.c b/drivers/gpu/drm/etnaviv/etnaviv_sched.c
> >>> index feb6da1b6ceb..05f412204118 100644
> >>> --- a/drivers/gpu/drm/etnaviv/etnaviv_sched.c
> >>> +++ b/drivers/gpu/drm/etnaviv/etnaviv_sched.c
> >>> @@ -163,6 +163,8 @@ int etnaviv_sched_push_job(struct drm_sched_entity *sched_entity,
> >>> if (ret)
> >>> goto out_unlock;
> >>>
> >>> + drm_sched_job_arm(&submit->sched_job);
> >>> +
> >>> submit->out_fence = dma_fence_get(&submit->sched_job.s_fence->finished);
> >>> submit->out_fence_id = idr_alloc_cyclic(&submit->gpu->fence_idr,
> >>> submit->out_fence, 0,
> >>> diff --git a/drivers/gpu/drm/lima/lima_sched.c b/drivers/gpu/drm/lima/lima_sched.c
> >>> index dba8329937a3..38f755580507 100644
> >>> --- a/drivers/gpu/drm/lima/lima_sched.c
> >>> +++ b/drivers/gpu/drm/lima/lima_sched.c
> >>> @@ -129,6 +129,8 @@ int lima_sched_task_init(struct lima_sched_task *task,
> >>> return err;
> >>> }
> >>>
> >>> + drm_sched_job_arm(&task->base);
> >>> +
> >>> task->num_bos = num_bos;
> >>> task->vm = lima_vm_get(vm);
> >>>
> >>> diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c
> >>> index fdc5367aecaa..6d6c44f0e1f3 100644
> >>> --- a/drivers/gpu/drm/msm/msm_gem_submit.c
> >>> +++ b/drivers/gpu/drm/msm/msm_gem_submit.c
> >>> @@ -52,6 +52,9 @@ static struct msm_gem_submit *submit_create(struct drm_device *dev,
> >>> return ERR_PTR(ret);
> >>> }
> >>>
> >>> + /* FIXME: this is way too early */
> >>> + drm_sched_job_arm(&job->base);
> >>> +
> >>> xa_init_flags(&submit->deps, XA_FLAGS_ALLOC);
> >>>
> >>> kref_init(&submit->ref);
> >>> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> >>> index 71a72fb50e6b..2992dc85325f 100644
> >>> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> >>> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> >>> @@ -288,6 +288,8 @@ int panfrost_job_push(struct panfrost_job *job)
> >>> goto unlock;
> >>> }
> >>>
> >>> + drm_sched_job_arm(&job->base);
> >>> +
> >>> job->render_done_fence = dma_fence_get(&job->base.s_fence->finished);
> >>>
> >>> ret = panfrost_acquire_object_fences(job->bos, job->bo_count,
> >>> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> >>> index 79554aa4dbb1..f7347c284886 100644
> >>> --- a/drivers/gpu/drm/scheduler/sched_entity.c
> >>> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
> >>> @@ -485,9 +485,9 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity)
> >>> * @sched_job: job to submit
> >>> * @entity: scheduler entity
> >>> *
> >>> - * Note: To guarantee that the order of insertion to queue matches
> >>> - * the job's fence sequence number this function should be
> >>> - * called with drm_sched_job_init under common lock.
> >>> + * Note: To guarantee that the order of insertion to queue matches the job's
> >>> + * fence sequence number this function should be called with drm_sched_job_arm()
> >>> + * under common lock.
> >>> *
> >>> * Returns 0 for success, negative error code otherwise.
> >>> */
> >>> diff --git a/drivers/gpu/drm/scheduler/sched_fence.c b/drivers/gpu/drm/scheduler/sched_fence.c
> >>> index 69de2c76731f..bcea035cf4c6 100644
> >>> --- a/drivers/gpu/drm/scheduler/sched_fence.c
> >>> +++ b/drivers/gpu/drm/scheduler/sched_fence.c
> >>> @@ -90,7 +90,7 @@ static const char *drm_sched_fence_get_timeline_name(struct dma_fence *f)
> >>> *
> >>> * Free up the fence memory after the RCU grace period.
> >>> */
> >>> -static void drm_sched_fence_free(struct rcu_head *rcu)
> >>> +void drm_sched_fence_free(struct rcu_head *rcu)
> >>> {
> >>> struct dma_fence *f = container_of(rcu, struct dma_fence, rcu);
> >>> struct drm_sched_fence *fence = to_drm_sched_fence(f);
> >>> @@ -152,27 +152,32 @@ struct drm_sched_fence *to_drm_sched_fence(struct dma_fence *f)
> >>> }
> >>> EXPORT_SYMBOL(to_drm_sched_fence);
> >>>
> >>> -struct drm_sched_fence *drm_sched_fence_create(struct drm_sched_entity *entity,
> >>> - void *owner)
> >>> +struct drm_sched_fence *drm_sched_fence_alloc(struct drm_sched_entity *entity,
> >>> + void *owner)
> >>> {
> >>> struct drm_sched_fence *fence = NULL;
> >>> - unsigned seq;
> >>>
> >>> fence = kmem_cache_zalloc(sched_fence_slab, GFP_KERNEL);
> >>> if (fence == NULL)
> >>> return NULL;
> >>>
> >>> fence->owner = owner;
> >>> - fence->sched = entity->rq->sched;
> >>> spin_lock_init(&fence->lock);
> >>>
> >>> + return fence;
> >>> +}
> >>> +
> >>> +void drm_sched_fence_init(struct drm_sched_fence *fence,
> >>> + struct drm_sched_entity *entity)
> >>> +{
> >>> + unsigned seq;
> >>> +
> >>> + fence->sched = entity->rq->sched;
> >>> seq = atomic_inc_return(&entity->fence_seq);
> >>> dma_fence_init(&fence->scheduled, &drm_sched_fence_ops_scheduled,
> >>> &fence->lock, entity->fence_context, seq);
> >>> dma_fence_init(&fence->finished, &drm_sched_fence_ops_finished,
> >>> &fence->lock, entity->fence_context + 1, seq);
> >>> -
> >>> - return fence;
> >>> }
> >>>
> >>> module_init(drm_sched_fence_slab_init);
> >>> diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
> >>> index 33c414d55fab..454cb6164bdc 100644
> >>> --- a/drivers/gpu/drm/scheduler/sched_main.c
> >>> +++ b/drivers/gpu/drm/scheduler/sched_main.c
> >>> @@ -48,9 +48,11 @@
> >>> #include <linux/wait.h>
> >>> #include <linux/sched.h>
> >>> #include <linux/completion.h>
> >>> +#include <linux/dma-resv.h>
> >>> #include <uapi/linux/sched/types.h>
> >>>
> >>> #include <drm/drm_print.h>
> >>> +#include <drm/drm_gem.h>
> >>> #include <drm/gpu_scheduler.h>
> >>> #include <drm/spsc_queue.h>
> >>>
> >>> @@ -569,7 +571,6 @@ EXPORT_SYMBOL(drm_sched_resubmit_jobs_ext);
> >>>
> >>> /**
> >>> * drm_sched_job_init - init a scheduler job
> >>> - *
> >>> * @job: scheduler job to init
> >>> * @entity: scheduler entity to use
> >>> * @owner: job owner for debugging
> >>> @@ -577,27 +578,28 @@ EXPORT_SYMBOL(drm_sched_resubmit_jobs_ext);
> >>> * Refer to drm_sched_entity_push_job() documentation
> >>> * for locking considerations.
> >>> *
> >>> + * Drivers must make sure drm_sched_job_cleanup() if this function returns
> >>> + * successfully, even when @job is aborted before drm_sched_job_arm() is called.
> >>> + *
> >>> + * WARNING: amdgpu abuses &drm_sched.ready to signal when the hardware
> >>> + * has died, which can mean that there's no valid runqueue for a @entity.
> >>> + * This function returns -ENOENT in this case (which probably should be -EIO as
> >>> + * a more meanigful return value).
> >>> + *
> >>> * Returns 0 for success, negative error code otherwise.
> >>> */
> >>> int drm_sched_job_init(struct drm_sched_job *job,
> >>> struct drm_sched_entity *entity,
> >>> void *owner)
> >>> {
> >>> - struct drm_gpu_scheduler *sched;
> >>> -
> >>> drm_sched_entity_select_rq(entity);
> >>> if (!entity->rq)
> >>> return -ENOENT;
> >>>
> >>> - sched = entity->rq->sched;
> >>> -
> >>> - job->sched = sched;
> >>> job->entity = entity;
> >>> - job->s_priority = entity->rq - sched->sched_rq;
> >>> - job->s_fence = drm_sched_fence_create(entity, owner);
> >>> + job->s_fence = drm_sched_fence_alloc(entity, owner);
> >>> if (!job->s_fence)
> >>> return -ENOMEM;
> >>> - job->id = atomic64_inc_return(&sched->job_id_count);
> >>>
> >>> INIT_LIST_HEAD(&job->list);
> >>>
> >>> @@ -606,13 +608,58 @@ int drm_sched_job_init(struct drm_sched_job *job,
> >>> EXPORT_SYMBOL(drm_sched_job_init);
> >>>
> >>> /**
> >>> - * drm_sched_job_cleanup - clean up scheduler job resources
> >>> + * drm_sched_job_arm - arm a scheduler job for execution
> >>> + * @job: scheduler job to arm
> >>> + *
> >>> + * This arms a scheduler job for execution. Specifically it initializes the
> >>> + * &drm_sched_job.s_fence of @job, so that it can be attached to struct dma_resv
> >>> + * or other places that need to track the completion of this job.
> >>> + *
> >>> + * Refer to drm_sched_entity_push_job() documentation for locking
> >>> + * considerations.
> >>> *
> >>> + * This can only be called if drm_sched_job_init() succeeded.
> >>> + */
> >>> +void drm_sched_job_arm(struct drm_sched_job *job)
> >>> +{
> >>> + struct drm_gpu_scheduler *sched;
> >>> + struct drm_sched_entity *entity = job->entity;
> >>> +
> >>> + BUG_ON(!entity);
> >>> +
> >>> + sched = entity->rq->sched;
> >>> +
> >>> + job->sched = sched;
> >>> + job->s_priority = entity->rq - sched->sched_rq;
> >>> + job->id = atomic64_inc_return(&sched->job_id_count);
> >>> +
> >>> + drm_sched_fence_init(job->s_fence, job->entity);
> >>> +}
> >>> +EXPORT_SYMBOL(drm_sched_job_arm);
> >>> +
> >>> +/**
> >>> + * drm_sched_job_cleanup - clean up scheduler job resources
> >>> * @job: scheduler job to clean up
> >>> + *
> >>> + * Cleans up the resources allocated with drm_sched_job_init().
> >>> + *
> >>> + * Drivers should call this from their error unwind code if @job is aborted
> >>> + * before drm_sched_job_arm() is called.
> >>> + *
> >>> + * After that point of no return @job is committed to be executed by the
> >>> + * scheduler, and this function should be called from the
> >>> + * &drm_sched_backend_ops.free_job callback.
> >>> */
> >>> void drm_sched_job_cleanup(struct drm_sched_job *job)
> >>> {
> >>> - dma_fence_put(&job->s_fence->finished);
> >>> + if (kref_read(&job->s_fence->finished.refcount)) {
> >>> + /* drm_sched_job_arm() has been called */
> >>> + dma_fence_put(&job->s_fence->finished);
> >>> + } else {
> >>> + /* aborted job before committing to run it */
> >>> + drm_sched_fence_free(&job->s_fence->finished.rcu);
> >>> + }
> >>> +
> >>> job->s_fence = NULL;
> >>> }
> >>> EXPORT_SYMBOL(drm_sched_job_cleanup);
> >>> diff --git a/drivers/gpu/drm/v3d/v3d_gem.c b/drivers/gpu/drm/v3d/v3d_gem.c
> >>> index 5689da118197..2e808097b4d1 100644
> >>> --- a/drivers/gpu/drm/v3d/v3d_gem.c
> >>> +++ b/drivers/gpu/drm/v3d/v3d_gem.c
> >>> @@ -480,6 +480,8 @@ v3d_push_job(struct v3d_file_priv *v3d_priv,
> >>> if (ret)
> >>> return ret;
> >>>
> >>> + drm_sched_job_arm(&job->base);
> >>> +
> >>> job->done_fence = dma_fence_get(&job->base.s_fence->finished);
> >>>
> >>> /* put by scheduler job completion */
> >>> diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
> >>> index 88ae7f331bb1..83afc3aa8e2f 100644
> >>> --- a/include/drm/gpu_scheduler.h
> >>> +++ b/include/drm/gpu_scheduler.h
> >>> @@ -348,6 +348,7 @@ void drm_sched_fini(struct drm_gpu_scheduler *sched);
> >>> int drm_sched_job_init(struct drm_sched_job *job,
> >>> struct drm_sched_entity *entity,
> >>> void *owner);
> >>> +void drm_sched_job_arm(struct drm_sched_job *job);
> >>> void drm_sched_entity_modify_sched(struct drm_sched_entity *entity,
> >>> struct drm_gpu_scheduler **sched_list,
> >>> unsigned int num_sched_list);
> >>> @@ -387,8 +388,12 @@ void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
> >>> enum drm_sched_priority priority);
> >>> bool drm_sched_entity_is_ready(struct drm_sched_entity *entity);
> >>>
> >>> -struct drm_sched_fence *drm_sched_fence_create(
> >>> +struct drm_sched_fence *drm_sched_fence_alloc(
> >>> struct drm_sched_entity *s_entity, void *owner);
> >>> +void drm_sched_fence_init(struct drm_sched_fence *fence,
> >>> + struct drm_sched_entity *entity);
> >>> +void drm_sched_fence_free(struct rcu_head *rcu);
> >>> +
> >>> void drm_sched_fence_scheduled(struct drm_sched_fence *fence);
> >>> void drm_sched_fence_finished(struct drm_sched_fence *fence);
> >>>
> >
>
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
