On Tue, Dec 03, 2019 at 06:33:08PM +0100, Daniel Vetter wrote:
> On Tue, Dec 03, 2019 at 05:32:03PM +0100, Thierry Reding wrote:
> > From: Thierry Reding <treding@xxxxxxxxxx>
> >
> > DMA-BUF requires that each device that accesses a DMA-BUF attaches to it
> > separately. To do so the host1x_bo_pin() and host1x_bo_unpin() functions
> > need to be reimplemented so that they can return a mapping, which either
> > represents an attachment or a map of the driver's own GEM object.
> >
> > Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
>
> I didn't check the full details, but this looks like it's doing things as
> intended.
>
> Acked-by: Daniel Vetter <daniel.vetter@xxxxxxxx>
I forgot to add: I guess this could conflict with the cleanup I pushed
into drm-misc-next for 5.6. If that's the case either put these there too,
or wait until drm-misc-next has landed in drm-next before merging them to
some tegra tree.
-Daniel
>
> Cheers, Daniel
>
> > ---
> > drivers/gpu/drm/tegra/gem.c | 131 +++++++++++++++++++++-------------
> > drivers/gpu/drm/tegra/plane.c | 47 ++++--------
> > drivers/gpu/drm/tegra/plane.h | 2 +-
> > drivers/gpu/host1x/job.c | 127 ++++++++++++--------------------
> > drivers/gpu/host1x/job.h | 6 +-
> > include/linux/host1x.h | 32 ++++++---
> > 6 files changed, 162 insertions(+), 183 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/tegra/gem.c b/drivers/gpu/drm/tegra/gem.c
> > index 1237df157e05..c085499067ed 100644
> > --- a/drivers/gpu/drm/tegra/gem.c
> > +++ b/drivers/gpu/drm/tegra/gem.c
> > @@ -27,71 +27,77 @@ static void tegra_bo_put(struct host1x_bo *bo)
> > drm_gem_object_put_unlocked(&obj->gem);
> > }
> >
> > -/* XXX move this into lib/scatterlist.c? */
> > -static int sg_alloc_table_from_sg(struct sg_table *sgt, struct scatterlist *sg,
> > - unsigned int nents, gfp_t gfp_mask)
> > +static struct host1x_bo_mapping *
> > +tegra_bo_pin(struct device *dev, struct host1x_bo *bo,
> > + enum dma_data_direction direction)
> > {
> > - struct scatterlist *dst;
> > - unsigned int i;
> > + struct tegra_bo *obj = host1x_to_tegra_bo(bo);
> > + struct drm_gem_object *gem = &obj->gem;
> > + struct host1x_bo_mapping *map;
> > int err;
> >
> > - err = sg_alloc_table(sgt, nents, gfp_mask);
> > - if (err < 0)
> > - return err;
> > -
> > - dst = sgt->sgl;
> > + map = kzalloc(sizeof(*map), GFP_KERNEL);
> > + if (!map)
> > + return ERR_PTR(-ENOMEM);
> >
> > - for (i = 0; i < nents; i++) {
> > - sg_set_page(dst, sg_page(sg), sg->length, 0);
> > - dst = sg_next(dst);
> > - sg = sg_next(sg);
> > - }
> > -
> > - return 0;
> > -}
> > -
> > -static struct sg_table *tegra_bo_pin(struct device *dev, struct host1x_bo *bo,
> > - dma_addr_t *phys)
> > -{
> > - struct tegra_bo *obj = host1x_to_tegra_bo(bo);
> > - struct sg_table *sgt;
> > - int err;
> > + map->direction = direction;
> > + map->dev = dev;
> > + map->bo = bo;
> >
> > /*
> > * If we've manually mapped the buffer object through the IOMMU, make
> > * sure to return the IOVA address of our mapping.
> > */
> > - if (phys && obj->mm) {
> > - *phys = obj->iova;
> > - return NULL;
> > + if (obj->mm) {
> > + map->phys = obj->iova;
> > + return map;
> > + }
> > +
> > + /*
> > + * Imported buffers need special treatment to satisfy the semantics of
> > + * DMA-BUF.
> > + */
> > + if (gem->import_attach) {
> > + struct dma_buf *buf = gem->import_attach->dmabuf;
> > +
> > + map->attach = dma_buf_attach(buf, dev);
> > + if (IS_ERR(map->attach)) {
> > + err = PTR_ERR(map->attach);
> > + goto free;
> > + }
> > +
> > + map->sgt = dma_buf_map_attachment(map->attach, direction);
> > + if (IS_ERR(map->sgt)) {
> > + dma_buf_detach(buf, map->attach);
> > + err = PTR_ERR(map->sgt);
> > + goto free;
> > + }
> > +
> > + map->chunks = sgt_dma_count_chunks(map->sgt);
> > + map->phys = sg_dma_address(map->sgt->sgl);
> > + map->size = gem->size;
> > +
> > + return map;
> > }
> >
> > /*
> > * If we don't have a mapping for this buffer yet, return an SG table
> > * so that host1x can do the mapping for us via the DMA API.
> > */
> > - sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
> > - if (!sgt)
> > - return ERR_PTR(-ENOMEM);
> > + map->sgt = kzalloc(sizeof(*map->sgt), GFP_KERNEL);
> > + if (!map->sgt) {
> > + err = -ENOMEM;
> > + goto free;
> > + }
> >
> > if (obj->pages) {
> > /*
> > * If the buffer object was allocated from the explicit IOMMU
> > * API code paths, construct an SG table from the pages.
> > */
> > - err = sg_alloc_table_from_pages(sgt, obj->pages, obj->num_pages,
> > - 0, obj->gem.size, GFP_KERNEL);
> > - if (err < 0)
> > - goto free;
> > - } else if (obj->sgt) {
> > - /*
> > - * If the buffer object already has an SG table but no pages
> > - * were allocated for it, it means the buffer was imported and
> > - * the SG table needs to be copied to avoid overwriting any
> > - * other potential users of the original SG table.
> > - */
> > - err = sg_alloc_table_from_sg(sgt, obj->sgt->sgl, obj->sgt->nents,
> > - GFP_KERNEL);
> > + err = sg_alloc_table_from_pages(map->sgt, obj->pages,
> > + obj->num_pages, 0,
> > + obj->gem.size, GFP_KERNEL);
> > if (err < 0)
> > goto free;
> > } else {
> > @@ -100,25 +106,48 @@ static struct sg_table *tegra_bo_pin(struct device *dev, struct host1x_bo *bo,
> > * not imported, it had to be allocated with the DMA API, so
> > * the DMA API helper can be used.
> > */
> > - err = dma_get_sgtable(dev, sgt, obj->vaddr, obj->iova,
> > + err = dma_get_sgtable(dev, map->sgt, obj->vaddr, obj->iova,
> > obj->gem.size);
> > if (err < 0)
> > goto free;
> > }
> >
> > - return sgt;
> > + err = dma_map_sg(dev, map->sgt->sgl, map->sgt->nents, direction);
> > + if (!err) {
> > + err = -ENOMEM;
> > + goto free_sgt;
> > + }
> > +
> > + map->phys = sg_dma_address(map->sgt->sgl);
> > + map->size = gem->size;
> > + map->chunks = err;
> > +
> > + return map;
> >
> > +free_sgt:
> > + sg_free_table(map->sgt);
> > free:
> > - kfree(sgt);
> > + kfree(map->sgt);
> > + kfree(map);
> > return ERR_PTR(err);
> > }
> >
> > -static void tegra_bo_unpin(struct device *dev, struct sg_table *sgt)
> > +static void tegra_bo_unpin(struct host1x_bo_mapping *map)
> > {
> > - if (sgt) {
> > - sg_free_table(sgt);
> > - kfree(sgt);
> > + if (!map)
> > + return;
> > +
> > + if (map->attach) {
> > + dma_buf_unmap_attachment(map->attach, map->sgt, map->direction);
> > + dma_buf_detach(map->attach->dmabuf, map->attach);
> > + } else {
> > + dma_unmap_sg(map->dev, map->sgt->sgl, map->sgt->nents,
> > + map->direction);
> > + sg_free_table(map->sgt);
> > + kfree(map->sgt);
> > }
> > +
> > + kfree(map);
> > }
> >
> > static void *tegra_bo_mmap(struct host1x_bo *bo)
> > diff --git a/drivers/gpu/drm/tegra/plane.c b/drivers/gpu/drm/tegra/plane.c
> > index cadcdd9ea427..28cf668026da 100644
> > --- a/drivers/gpu/drm/tegra/plane.c
> > +++ b/drivers/gpu/drm/tegra/plane.c
> > @@ -67,7 +67,7 @@ tegra_plane_atomic_duplicate_state(struct drm_plane *plane)
> >
> > for (i = 0; i < 3; i++) {
> > copy->iova[i] = DMA_MAPPING_ERROR;
> > - copy->sgt[i] = NULL;
> > + copy->map[i] = NULL;
> > }
> >
> > return ©->base;
> > @@ -114,18 +114,11 @@ static int tegra_dc_pin(struct tegra_dc *dc, struct tegra_plane_state *state)
> > struct tegra_bo *bo = tegra_fb_get_plane(state->base.fb, i);
> >
> > if (!dc->client.group) {
> > - struct sg_table *sgt;
> > + struct host1x_bo_mapping *map;
> >
> > - sgt = host1x_bo_pin(dc->dev, &bo->base, NULL);
> > - if (IS_ERR(sgt)) {
> > - err = PTR_ERR(sgt);
> > - goto unpin;
> > - }
> > -
> > - err = dma_map_sg(dc->dev, sgt->sgl, sgt->nents,
> > - DMA_TO_DEVICE);
> > - if (err == 0) {
> > - err = -ENOMEM;
> > + map = host1x_bo_pin(dc->dev, &bo->base, DMA_TO_DEVICE);
> > + if (IS_ERR(map)) {
> > + err = PTR_ERR(map);
> > goto unpin;
> > }
> >
> > @@ -135,13 +128,13 @@ static int tegra_dc_pin(struct tegra_dc *dc, struct tegra_plane_state *state)
> > * map its SG table to a single contiguous chunk of
> > * I/O virtual memory.
> > */
> > - if (err > 1) {
> > + if (map->chunks > 1) {
> > err = -EINVAL;
> > goto unpin;
> > }
> >
> > - state->iova[i] = sg_dma_address(sgt->sgl);
> > - state->sgt[i] = sgt;
> > + state->iova[i] = map->phys;
> > + state->map[i] = map;
> > } else {
> > state->iova[i] = bo->iova;
> > }
> > @@ -153,14 +146,9 @@ static int tegra_dc_pin(struct tegra_dc *dc, struct tegra_plane_state *state)
> > dev_err(dc->dev, "failed to map plane %u: %d\n", i, err);
> >
> > while (i--) {
> > - struct tegra_bo *bo = tegra_fb_get_plane(state->base.fb, i);
> > - struct sg_table *sgt = state->sgt[i];
> > -
> > - dma_unmap_sg(dc->dev, sgt->sgl, sgt->nents, DMA_TO_DEVICE);
> > - host1x_bo_unpin(dc->dev, &bo->base, sgt);
> > -
> > + host1x_bo_unpin(state->map[i]);
> > state->iova[i] = DMA_MAPPING_ERROR;
> > - state->sgt[i] = NULL;
> > + state->map[i] = NULL;
> > }
> >
> > return err;
> > @@ -171,20 +159,11 @@ static void tegra_dc_unpin(struct tegra_dc *dc, struct tegra_plane_state *state)
> > unsigned int i;
> >
> > for (i = 0; i < state->base.fb->format->num_planes; i++) {
> > - struct tegra_bo *bo = tegra_fb_get_plane(state->base.fb, i);
> > -
> > - if (!dc->client.group) {
> > - struct sg_table *sgt = state->sgt[i];
> > -
> > - if (sgt) {
> > - dma_unmap_sg(dc->dev, sgt->sgl, sgt->nents,
> > - DMA_TO_DEVICE);
> > - host1x_bo_unpin(dc->dev, &bo->base, sgt);
> > - }
> > - }
> > + if (!dc->client.group)
> > + host1x_bo_unpin(state->map[i]);
> >
> > state->iova[i] = DMA_MAPPING_ERROR;
> > - state->sgt[i] = NULL;
> > + state->map[i] = NULL;
> > }
> > }
> >
> > diff --git a/drivers/gpu/drm/tegra/plane.h b/drivers/gpu/drm/tegra/plane.h
> > index a158a915109a..08df1ba1f567 100644
> > --- a/drivers/gpu/drm/tegra/plane.h
> > +++ b/drivers/gpu/drm/tegra/plane.h
> > @@ -39,7 +39,7 @@ struct tegra_plane_legacy_blending_state {
> > struct tegra_plane_state {
> > struct drm_plane_state base;
> >
> > - struct sg_table *sgt[3];
> > + struct host1x_bo_mapping *map[3];
> > dma_addr_t iova[3];
> >
> > struct tegra_bo_tiling tiling;
> > diff --git a/drivers/gpu/host1x/job.c b/drivers/gpu/host1x/job.c
> > index 60b2fedd0061..88e445553df3 100644
> > --- a/drivers/gpu/host1x/job.c
> > +++ b/drivers/gpu/host1x/job.c
> > @@ -99,6 +99,7 @@ EXPORT_SYMBOL(host1x_job_add_gather);
> >
> > static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
> > {
> > + unsigned long mask = HOST1X_RELOC_READ | HOST1X_RELOC_WRITE;
> > struct host1x_client *client = job->client;
> > struct device *dev = client->dev;
> > unsigned int i;
> > @@ -108,8 +109,8 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
> >
> > for (i = 0; i < job->num_relocs; i++) {
> > struct host1x_reloc *reloc = &job->relocs[i];
> > - dma_addr_t phys_addr, *phys;
> > - struct sg_table *sgt;
> > + enum dma_data_direction direction;
> > + struct host1x_bo_mapping *map;
> >
> > reloc->target.bo = host1x_bo_get(reloc->target.bo);
> > if (!reloc->target.bo) {
> > @@ -117,63 +118,40 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
> > goto unpin;
> > }
> >
> > - if (client->group)
> > - phys = &phys_addr;
> > - else
> > - phys = NULL;
> > -
> > - sgt = host1x_bo_pin(dev, reloc->target.bo, phys);
> > - if (IS_ERR(sgt)) {
> > - err = PTR_ERR(sgt);
> > - goto unpin;
> > - }
> > -
> > - if (sgt) {
> > - unsigned long mask = HOST1X_RELOC_READ |
> > - HOST1X_RELOC_WRITE;
> > - enum dma_data_direction dir;
> > -
> > - switch (reloc->flags & mask) {
> > - case HOST1X_RELOC_READ:
> > - dir = DMA_TO_DEVICE;
> > - break;
> > -
> > - case HOST1X_RELOC_WRITE:
> > - dir = DMA_FROM_DEVICE;
> > - break;
> > + switch (reloc->flags & mask) {
> > + case HOST1X_RELOC_READ:
> > + direction = DMA_TO_DEVICE;
> > + break;
> >
> > - case HOST1X_RELOC_READ | HOST1X_RELOC_WRITE:
> > - dir = DMA_BIDIRECTIONAL;
> > - break;
> > + case HOST1X_RELOC_WRITE:
> > + direction = DMA_FROM_DEVICE;
> > + break;
> >
> > - default:
> > - err = -EINVAL;
> > - goto unpin;
> > - }
> > + case HOST1X_RELOC_READ | HOST1X_RELOC_WRITE:
> > + direction = DMA_BIDIRECTIONAL;
> > + break;
> >
> > - err = dma_map_sg(dev, sgt->sgl, sgt->nents, dir);
> > - if (!err) {
> > - err = -ENOMEM;
> > - goto unpin;
> > - }
> > + default:
> > + err = -EINVAL;
> > + goto unpin;
> > + }
> >
> > - job->unpins[job->num_unpins].dev = dev;
> > - job->unpins[job->num_unpins].dir = dir;
> > - phys_addr = sg_dma_address(sgt->sgl);
> > + map = host1x_bo_pin(dev, reloc->target.bo, direction);
> > + if (IS_ERR(map)) {
> > + err = PTR_ERR(map);
> > + goto unpin;
> > }
> >
> > - job->addr_phys[job->num_unpins] = phys_addr;
> > - job->unpins[job->num_unpins].bo = reloc->target.bo;
> > - job->unpins[job->num_unpins].sgt = sgt;
> > + job->addr_phys[job->num_unpins] = map->phys;
> > + job->unpins[job->num_unpins].map = map;
> > job->num_unpins++;
> > }
> >
> > for (i = 0; i < job->num_gathers; i++) {
> > struct host1x_job_gather *g = &job->gathers[i];
> > + struct host1x_bo_mapping *map;
> > size_t gather_size = 0;
> > struct scatterlist *sg;
> > - struct sg_table *sgt;
> > - dma_addr_t phys_addr;
> > unsigned long shift;
> > struct iova *alloc;
> > unsigned int j;
> > @@ -184,15 +162,16 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
> > goto unpin;
> > }
> >
> > - sgt = host1x_bo_pin(host->dev, g->bo, NULL);
> > - if (IS_ERR(sgt)) {
> > - err = PTR_ERR(sgt);
> > + map = host1x_bo_pin(host->dev, g->bo, DMA_TO_DEVICE);
> > + if (IS_ERR(map)) {
> > + err = PTR_ERR(map);
> > goto unpin;
> > }
> >
> > if (!IS_ENABLED(CONFIG_TEGRA_HOST1X_FIREWALL) && host->domain) {
> > - for_each_sg(sgt->sgl, sg, sgt->nents, j)
> > + for_each_sg(map->sgt->sgl, sg, map->sgt->nents, j)
> > gather_size += sg->length;
> > +
> > gather_size = iova_align(&host->iova, gather_size);
> >
> > shift = iova_shift(&host->iova);
> > @@ -204,35 +183,24 @@ static unsigned int pin_job(struct host1x *host, struct host1x_job *job)
> > }
> >
> > err = iommu_map_sg(host->domain,
> > - iova_dma_addr(&host->iova, alloc),
> > - sgt->sgl, sgt->nents, IOMMU_READ);
> > + iova_dma_addr(&host->iova, alloc),
> > + map->sgt->sgl, map->sgt->nents,
> > + IOMMU_READ);
> > if (err == 0) {
> > __free_iova(&host->iova, alloc);
> > err = -EINVAL;
> > goto unpin;
> > }
> >
> > - job->unpins[job->num_unpins].size = gather_size;
> > - phys_addr = iova_dma_addr(&host->iova, alloc);
> > - } else {
> > - err = dma_map_sg(host->dev, sgt->sgl, sgt->nents,
> > - DMA_TO_DEVICE);
> > - if (!err) {
> > - err = -ENOMEM;
> > - goto unpin;
> > - }
> > -
> > - job->unpins[job->num_unpins].dev = host->dev;
> > - phys_addr = sg_dma_address(sgt->sgl);
> > + map->phys = iova_dma_addr(&host->iova, alloc);
> > + map->size = gather_size;
> > }
> >
> > - job->addr_phys[job->num_unpins] = phys_addr;
> > - job->gather_addr_phys[i] = phys_addr;
> > -
> > - job->unpins[job->num_unpins].dir = DMA_TO_DEVICE;
> > - job->unpins[job->num_unpins].bo = g->bo;
> > - job->unpins[job->num_unpins].sgt = sgt;
> > + job->addr_phys[job->num_unpins] = map->phys;
> > + job->unpins[job->num_unpins].map = map;
> > job->num_unpins++;
> > +
> > + job->gather_addr_phys[i] = map->phys;
> > }
> >
> > return 0;
> > @@ -608,24 +576,19 @@ void host1x_job_unpin(struct host1x_job *job)
> > unsigned int i;
> >
> > for (i = 0; i < job->num_unpins; i++) {
> > - struct host1x_job_unpin_data *unpin = &job->unpins[i];
> > - struct device *dev = unpin->dev ?: host->dev;
> > - struct sg_table *sgt = unpin->sgt;
> > + struct host1x_bo_mapping *map = job->unpins[i].map;
> > + struct host1x_bo *bo = map->bo;
> >
> > if (!IS_ENABLED(CONFIG_TEGRA_HOST1X_FIREWALL) &&
> > - unpin->size && host->domain) {
> > + map->size && host->domain) {
> > iommu_unmap(host->domain, job->addr_phys[i],
> > - unpin->size);
> > + map->size);
> > free_iova(&host->iova,
> > - iova_pfn(&host->iova, job->addr_phys[i]));
> > + iova_pfn(&host->iova, job->addr_phys[i]));
> > }
> >
> > - if (unpin->dev && sgt)
> > - dma_unmap_sg(unpin->dev, sgt->sgl, sgt->nents,
> > - unpin->dir);
> > -
> > - host1x_bo_unpin(dev, unpin->bo, sgt);
> > - host1x_bo_put(unpin->bo);
> > + host1x_bo_unpin(map);
> > + host1x_bo_put(bo);
> > }
> >
> > job->num_unpins = 0;
> > diff --git a/drivers/gpu/host1x/job.h b/drivers/gpu/host1x/job.h
> > index 94bc2e4ae241..c28eebb8ce14 100644
> > --- a/drivers/gpu/host1x/job.h
> > +++ b/drivers/gpu/host1x/job.h
> > @@ -19,11 +19,7 @@ struct host1x_job_gather {
> > };
> >
> > struct host1x_job_unpin_data {
> > - struct host1x_bo *bo;
> > - struct sg_table *sgt;
> > - struct device *dev;
> > - size_t size;
> > - enum dma_data_direction dir;
> > + struct host1x_bo_mapping *map;
> > };
> >
> > /*
> > diff --git a/include/linux/host1x.h b/include/linux/host1x.h
> > index 0254ebcdc0a7..f1e6fad19289 100644
> > --- a/include/linux/host1x.h
> > +++ b/include/linux/host1x.h
> > @@ -7,6 +7,7 @@
> > #define __LINUX_HOST1X_H
> >
> > #include <linux/device.h>
> > +#include <linux/dma-direction.h>
> > #include <linux/types.h>
> >
> > enum host1x_class {
> > @@ -72,12 +73,24 @@ struct host1x_client {
> > struct host1x_bo;
> > struct sg_table;
> >
> > +struct host1x_bo_mapping {
> > + struct dma_buf_attachment *attach;
> > + enum dma_data_direction direction;
> > + struct host1x_bo *bo;
> > + struct sg_table *sgt;
> > + unsigned int chunks;
> > + struct device *dev;
> > + dma_addr_t phys;
> > + size_t size;
> > +};
> > +
> > struct host1x_bo_ops {
> > struct host1x_bo *(*get)(struct host1x_bo *bo);
> > void (*put)(struct host1x_bo *bo);
> > - struct sg_table *(*pin)(struct device *dev, struct host1x_bo *bo,
> > - dma_addr_t *phys);
> > - void (*unpin)(struct device *dev, struct sg_table *sgt);
> > + struct host1x_bo_mapping *(*pin)(struct device *dev,
> > + struct host1x_bo *bo,
> > + enum dma_data_direction dir);
> > + void (*unpin)(struct host1x_bo_mapping *map);
> > void *(*mmap)(struct host1x_bo *bo);
> > void (*munmap)(struct host1x_bo *bo, void *addr);
> > };
> > @@ -102,17 +115,16 @@ static inline void host1x_bo_put(struct host1x_bo *bo)
> > bo->ops->put(bo);
> > }
> >
> > -static inline struct sg_table *host1x_bo_pin(struct device *dev,
> > - struct host1x_bo *bo,
> > - dma_addr_t *phys)
> > +static inline struct host1x_bo_mapping *
> > +host1x_bo_pin(struct device *dev, struct host1x_bo *bo,
> > + enum dma_data_direction dir)
> > {
> > - return bo->ops->pin(dev, bo, phys);
> > + return bo->ops->pin(dev, bo, dir);
> > }
> >
> > -static inline void host1x_bo_unpin(struct device *dev, struct host1x_bo *bo,
> > - struct sg_table *sgt)
> > +static inline void host1x_bo_unpin(struct host1x_bo_mapping *map)
> > {
> > - bo->ops->unpin(dev, sgt);
> > + map->bo->ops->unpin(map);
> > }
> >
> > static inline void *host1x_bo_mmap(struct host1x_bo *bo)
> > --
> > 2.23.0
> >
>
> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch
--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
