On Thu, 07 Apr 2022, Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
> On Thu, Apr 07, 2022 at 01:23:38PM +0300, Jani Nikula wrote:
>> On Wed, 06 Apr 2022, Ville Syrjala <ville.syrjala@xxxxxxxxxxxxxxx> wrote:
>> > From: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>> >
>> > Make a copy of each VB data block with a guaranteed minimum
>> > size. The extra (if any) will just be left zeroed.
>> >
>> > This means we don't have to worry about going out of bounds
>> > when accessing any of the structure members. Otherwise that
>> > could easliy happen if we simply get the version check wrong,
>> > or if the VBT is broken/malicious.
>> >
>> > v2: Don't do arithmetic between bdb header and copy
>> > of the LFP data block (Jani)
>> > v3: Make all the copies up front
>> > v4: Only WARN about min_size==0 if we found the block
>> >
>> > Signed-off-by: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
>> > ---
>> > drivers/gpu/drm/i915/display/intel_bios.c | 230 ++++++++++++++++------
>> > drivers/gpu/drm/i915/i915_drv.h | 1 +
>> > 2 files changed, 174 insertions(+), 57 deletions(-)
>> >
>> > diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
>> > index 5518f4cfa1b1..068978734e3b 100644
>> > --- a/drivers/gpu/drm/i915/display/intel_bios.c
>> > +++ b/drivers/gpu/drm/i915/display/intel_bios.c
>> > @@ -88,7 +88,7 @@ static u32 get_blocksize(const void *block_data)
>> > }
>> >
>> > static const void *
>> > -find_section(const void *_bdb, enum bdb_block_id section_id)
>> > +find_raw_section(const void *_bdb, enum bdb_block_id section_id)
>> > {
>> > const struct bdb_header *bdb = _bdb;
>> > const u8 *base = _bdb;
>> > @@ -118,6 +118,124 @@ find_section(const void *_bdb, enum bdb_block_id section_id)
>> > return NULL;
>> > }
>> >
>> > +/*
>> > + * Offset from the start of BDB to the start of the
>> > + * block data (just past the block header).
>> > + */
>> > +static u32 block_offset(const void *bdb, enum bdb_block_id section_id)
>> > +{
>> > + const void *block;
>> > +
>> > + block = find_raw_section(bdb, section_id);
>> > + if (!block)
>> > + return 0;
>> > +
>> > + return block - bdb;
>> > +}
>> > +
>> > +struct bdb_block_entry {
>> > + struct list_head node;
>> > + enum bdb_block_id section_id;
>> > + u8 data[];
>> > +};
>> > +
>> > +static const void *
>> > +find_section(struct drm_i915_private *i915,
>> > + enum bdb_block_id section_id)
>> > +{
>> > + struct bdb_block_entry *entry;
>> > +
>> > + list_for_each_entry(entry, &i915->vbt.bdb_blocks, node) {
>> > + if (entry->section_id == section_id)
>> > + return entry->data + 3;
>> > + }
>> > +
>>
>> Failing to find the section_id in the list above, perhaps this should
>> check if the section_id is present in bdb_blocks[] and complain
>> loudly. If we fail to add a section there, this will never find
>> it. I.e. we should never call find_section() on a section_id that isn't
>> present in bdb_blocks[].
>
> That's perfectly legit. Eg. old VBTs are always missing a lot
> of the eDP related blocks.
>
> What we could do is add some kind of dummy block into the list
> for every block we've initialized, whether we found it or not.
> With that we could complain if find_section() gets called on
> anything that we didn't try to duplicate.
I mean if we don't find it in the list, we can check the bdb_blocks[]
array if we even have it in our initialization list.
BR,
Jani.
>
>>
>> I also dislike the +/- 3 here and there.
>
> Yeah, I was pondering about defining a structure that actually includes
> the BDB block header and try to replace all the magic +/-3 stuff with
> that. But didn't feel like bloating this series any further right now.
>
>>
>> But both of these can be cleaned up later.
>>
>> Reviewed-by: Jani Nikula <jani.nikula@xxxxxxxxx>
>>
>>
>> > + return NULL;
>> > +}
>> > +
>> > +static const struct {
>> > + enum bdb_block_id section_id;
>> > + size_t min_size;
>> > +} bdb_blocks[] = {
>> > + { .section_id = BDB_GENERAL_FEATURES,
>> > + .min_size = sizeof(struct bdb_general_features), },
>> > + { .section_id = BDB_GENERAL_DEFINITIONS,
>> > + .min_size = sizeof(struct bdb_general_definitions), },
>> > + { .section_id = BDB_PSR,
>> > + .min_size = sizeof(struct bdb_psr), },
>> > + { .section_id = BDB_DRIVER_FEATURES,
>> > + .min_size = sizeof(struct bdb_driver_features), },
>> > + { .section_id = BDB_SDVO_LVDS_OPTIONS,
>> > + .min_size = sizeof(struct bdb_sdvo_lvds_options), },
>> > + { .section_id = BDB_SDVO_PANEL_DTDS,
>> > + .min_size = sizeof(struct bdb_sdvo_panel_dtds), },
>> > + { .section_id = BDB_EDP,
>> > + .min_size = sizeof(struct bdb_edp), },
>> > + { .section_id = BDB_LVDS_OPTIONS,
>> > + .min_size = sizeof(struct bdb_lvds_options), },
>> > + { .section_id = BDB_LVDS_LFP_DATA_PTRS,
>> > + .min_size = sizeof(struct bdb_lvds_lfp_data_ptrs), },
>> > + { .section_id = BDB_LVDS_LFP_DATA,
>> > + .min_size = sizeof(struct bdb_lvds_lfp_data), },
>> > + { .section_id = BDB_LVDS_BACKLIGHT,
>> > + .min_size = sizeof(struct bdb_lfp_backlight_data), },
>> > + { .section_id = BDB_LFP_POWER,
>> > + .min_size = sizeof(struct bdb_lfp_power), },
>> > + { .section_id = BDB_MIPI_CONFIG,
>> > + .min_size = sizeof(struct bdb_mipi_config), },
>> > + { .section_id = BDB_MIPI_SEQUENCE,
>> > + .min_size = sizeof(struct bdb_mipi_sequence) },
>> > + { .section_id = BDB_COMPRESSION_PARAMETERS,
>> > + .min_size = sizeof(struct bdb_compression_parameters), },
>> > + { .section_id = BDB_GENERIC_DTD,
>> > + .min_size = sizeof(struct bdb_generic_dtd), },
>> > +};
>> > +
>> > +static void
>> > +init_bdb_block(struct drm_i915_private *i915,
>> > + const void *bdb, enum bdb_block_id section_id,
>> > + size_t min_size)
>> > +{
>> > + struct bdb_block_entry *entry;
>> > + const void *block;
>> > + size_t block_size;
>> > +
>> > + block = find_raw_section(bdb, section_id);
>> > + if (!block)
>> > + return;
>> > +
>> > + drm_WARN(&i915->drm, min_size == 0,
>> > + "Block %d min_size is zero\n", section_id);
>> > +
>> > + block_size = get_blocksize(block);
>> > +
>> > + entry = kzalloc(struct_size(entry, data, max(min_size, block_size) + 3),
>> > + GFP_KERNEL);
>> > + if (!entry)
>> > + return;
>> > +
>> > + entry->section_id = section_id;
>> > + memcpy(entry->data, block - 3, block_size + 3);
>> > +
>> > + drm_dbg_kms(&i915->drm, "Found BDB block %d (size %zu, min size %zu)\n",
>> > + section_id, block_size, min_size);
>> > +
>> > + list_add_tail(&entry->node, &i915->vbt.bdb_blocks);
>> > +}
>> > +
>> > +static void init_bdb_blocks(struct drm_i915_private *i915,
>> > + const void *bdb)
>> > +{
>> > + int i;
>> > +
>> > + for (i = 0; i < ARRAY_SIZE(bdb_blocks); i++) {
>> > + enum bdb_block_id section_id = bdb_blocks[i].section_id;
>> > + size_t min_size = bdb_blocks[i].min_size;
>> > +
>> > + init_bdb_block(i915, bdb, section_id, min_size);
>> > + }
>> > +}
>> > +
>> > static void
>> > fill_detail_timing_data(struct drm_display_mode *panel_fixed_mode,
>> > const struct lvds_dvo_timing *dvo_timing)
>> > @@ -199,7 +317,7 @@ get_lvds_fp_timing(const struct bdb_header *bdb,
>> > const struct bdb_lvds_lfp_data_ptrs *ptrs,
>> > int index)
>> > {
>> > - size_t data_ofs = (const u8 *)data - (const u8 *)bdb;
>> > + size_t data_ofs = block_offset(bdb, BDB_LVDS_LFP_DATA);
>> > u16 data_size = ((const u16 *)data)[-1]; /* stored in header */
>> > size_t ofs;
>> >
>> > @@ -214,15 +332,14 @@ get_lvds_fp_timing(const struct bdb_header *bdb,
>> >
>> > /* Parse general panel options */
>> > static void
>> > -parse_panel_options(struct drm_i915_private *i915,
>> > - const struct bdb_header *bdb)
>> > +parse_panel_options(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_lvds_options *lvds_options;
>> > int panel_type;
>> > int drrs_mode;
>> > int ret;
>> >
>> > - lvds_options = find_section(bdb, BDB_LVDS_OPTIONS);
>> > + lvds_options = find_section(i915, BDB_LVDS_OPTIONS);
>> > if (!lvds_options)
>> > return;
>> >
>> > @@ -285,11 +402,11 @@ parse_lfp_panel_dtd(struct drm_i915_private *i915,
>> > struct drm_display_mode *panel_fixed_mode;
>> > int panel_type = i915->vbt.panel_type;
>> >
>> > - lvds_lfp_data = find_section(bdb, BDB_LVDS_LFP_DATA);
>> > + lvds_lfp_data = find_section(i915, BDB_LVDS_LFP_DATA);
>> > if (!lvds_lfp_data)
>> > return;
>> >
>> > - lvds_lfp_data_ptrs = find_section(bdb, BDB_LVDS_LFP_DATA_PTRS);
>> > + lvds_lfp_data_ptrs = find_section(i915, BDB_LVDS_LFP_DATA_PTRS);
>> > if (!lvds_lfp_data_ptrs)
>> > return;
>> >
>> > @@ -325,15 +442,14 @@ parse_lfp_panel_dtd(struct drm_i915_private *i915,
>> > }
>> >
>> > static void
>> > -parse_generic_dtd(struct drm_i915_private *i915,
>> > - const struct bdb_header *bdb)
>> > +parse_generic_dtd(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_generic_dtd *generic_dtd;
>> > const struct generic_dtd_entry *dtd;
>> > struct drm_display_mode *panel_fixed_mode;
>> > int num_dtd;
>> >
>> > - generic_dtd = find_section(bdb, BDB_GENERIC_DTD);
>> > + generic_dtd = find_section(i915, BDB_GENERIC_DTD);
>> > if (!generic_dtd)
>> > return;
>> >
>> > @@ -416,21 +532,20 @@ parse_panel_dtd(struct drm_i915_private *i915,
>> > * back to trying the old LFP block if that fails.
>> > */
>> > if (i915->vbt.version >= 229)
>> > - parse_generic_dtd(i915, bdb);
>> > + parse_generic_dtd(i915);
>> > if (!i915->vbt.lfp_lvds_vbt_mode)
>> > parse_lfp_panel_dtd(i915, bdb);
>> > }
>> >
>> > static void
>> > -parse_lfp_backlight(struct drm_i915_private *i915,
>> > - const struct bdb_header *bdb)
>> > +parse_lfp_backlight(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_lfp_backlight_data *backlight_data;
>> > const struct lfp_backlight_data_entry *entry;
>> > int panel_type = i915->vbt.panel_type;
>> > u16 level;
>> >
>> > - backlight_data = find_section(bdb, BDB_LVDS_BACKLIGHT);
>> > + backlight_data = find_section(i915, BDB_LVDS_BACKLIGHT);
>> > if (!backlight_data)
>> > return;
>> >
>> > @@ -514,8 +629,7 @@ parse_lfp_backlight(struct drm_i915_private *i915,
>> >
>> > /* Try to find sdvo panel data */
>> > static void
>> > -parse_sdvo_panel_data(struct drm_i915_private *i915,
>> > - const struct bdb_header *bdb)
>> > +parse_sdvo_panel_data(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_sdvo_panel_dtds *dtds;
>> > struct drm_display_mode *panel_fixed_mode;
>> > @@ -531,14 +645,14 @@ parse_sdvo_panel_data(struct drm_i915_private *i915,
>> > if (index == -1) {
>> > const struct bdb_sdvo_lvds_options *sdvo_lvds_options;
>> >
>> > - sdvo_lvds_options = find_section(bdb, BDB_SDVO_LVDS_OPTIONS);
>> > + sdvo_lvds_options = find_section(i915, BDB_SDVO_LVDS_OPTIONS);
>> > if (!sdvo_lvds_options)
>> > return;
>> >
>> > index = sdvo_lvds_options->panel_type;
>> > }
>> >
>> > - dtds = find_section(bdb, BDB_SDVO_PANEL_DTDS);
>> > + dtds = find_section(i915, BDB_SDVO_PANEL_DTDS);
>> > if (!dtds)
>> > return;
>> >
>> > @@ -570,12 +684,11 @@ static int intel_bios_ssc_frequency(struct drm_i915_private *i915,
>> > }
>> >
>> > static void
>> > -parse_general_features(struct drm_i915_private *i915,
>> > - const struct bdb_header *bdb)
>> > +parse_general_features(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_general_features *general;
>> >
>> > - general = find_section(bdb, BDB_GENERAL_FEATURES);
>> > + general = find_section(i915, BDB_GENERAL_FEATURES);
>> > if (!general)
>> > return;
>> >
>> > @@ -695,12 +808,11 @@ parse_sdvo_device_mapping(struct drm_i915_private *i915)
>> > }
>> >
>> > static void
>> > -parse_driver_features(struct drm_i915_private *i915,
>> > - const struct bdb_header *bdb)
>> > +parse_driver_features(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_driver_features *driver;
>> >
>> > - driver = find_section(bdb, BDB_DRIVER_FEATURES);
>> > + driver = find_section(i915, BDB_DRIVER_FEATURES);
>> > if (!driver)
>> > return;
>> >
>> > @@ -747,8 +859,7 @@ parse_driver_features(struct drm_i915_private *i915,
>> > }
>> >
>> > static void
>> > -parse_power_conservation_features(struct drm_i915_private *i915,
>> > - const struct bdb_header *bdb)
>> > +parse_power_conservation_features(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_lfp_power *power;
>> > u8 panel_type = i915->vbt.panel_type;
>> > @@ -756,7 +867,7 @@ parse_power_conservation_features(struct drm_i915_private *i915,
>> > if (i915->vbt.version < 228)
>> > return;
>> >
>> > - power = find_section(bdb, BDB_LFP_POWER);
>> > + power = find_section(i915, BDB_LFP_POWER);
>> > if (!power)
>> > return;
>> >
>> > @@ -776,14 +887,14 @@ parse_power_conservation_features(struct drm_i915_private *i915,
>> > }
>> >
>> > static void
>> > -parse_edp(struct drm_i915_private *i915, const struct bdb_header *bdb)
>> > +parse_edp(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_edp *edp;
>> > const struct edp_power_seq *edp_pps;
>> > const struct edp_fast_link_params *edp_link_params;
>> > int panel_type = i915->vbt.panel_type;
>> >
>> > - edp = find_section(bdb, BDB_EDP);
>> > + edp = find_section(i915, BDB_EDP);
>> > if (!edp)
>> > return;
>> >
>> > @@ -894,13 +1005,13 @@ parse_edp(struct drm_i915_private *i915, const struct bdb_header *bdb)
>> > }
>> >
>> > static void
>> > -parse_psr(struct drm_i915_private *i915, const struct bdb_header *bdb)
>> > +parse_psr(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_psr *psr;
>> > const struct psr_table *psr_table;
>> > int panel_type = i915->vbt.panel_type;
>> >
>> > - psr = find_section(bdb, BDB_PSR);
>> > + psr = find_section(i915, BDB_PSR);
>> > if (!psr) {
>> > drm_dbg_kms(&i915->drm, "No PSR BDB found.\n");
>> > return;
>> > @@ -1034,8 +1145,7 @@ static void parse_dsi_backlight_ports(struct drm_i915_private *i915,
>> > }
>> >
>> > static void
>> > -parse_mipi_config(struct drm_i915_private *i915,
>> > - const struct bdb_header *bdb)
>> > +parse_mipi_config(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_mipi_config *start;
>> > const struct mipi_config *config;
>> > @@ -1058,7 +1168,7 @@ parse_mipi_config(struct drm_i915_private *i915,
>> > /* Parse #52 for panel index used from panel_type already
>> > * parsed
>> > */
>> > - start = find_section(bdb, BDB_MIPI_CONFIG);
>> > + start = find_section(i915, BDB_MIPI_CONFIG);
>> > if (!start) {
>> > drm_dbg_kms(&i915->drm, "No MIPI config BDB found");
>> > return;
>> > @@ -1354,8 +1464,7 @@ static void fixup_mipi_sequences(struct drm_i915_private *i915)
>> > }
>> >
>> > static void
>> > -parse_mipi_sequence(struct drm_i915_private *i915,
>> > - const struct bdb_header *bdb)
>> > +parse_mipi_sequence(struct drm_i915_private *i915)
>> > {
>> > int panel_type = i915->vbt.panel_type;
>> > const struct bdb_mipi_sequence *sequence;
>> > @@ -1368,7 +1477,7 @@ parse_mipi_sequence(struct drm_i915_private *i915,
>> > if (i915->vbt.dsi.panel_id != MIPI_DSI_GENERIC_PANEL_ID)
>> > return;
>> >
>> > - sequence = find_section(bdb, BDB_MIPI_SEQUENCE);
>> > + sequence = find_section(i915, BDB_MIPI_SEQUENCE);
>> > if (!sequence) {
>> > drm_dbg_kms(&i915->drm,
>> > "No MIPI Sequence found, parsing complete\n");
>> > @@ -1439,8 +1548,7 @@ parse_mipi_sequence(struct drm_i915_private *i915,
>> > }
>> >
>> > static void
>> > -parse_compression_parameters(struct drm_i915_private *i915,
>> > - const struct bdb_header *bdb)
>> > +parse_compression_parameters(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_compression_parameters *params;
>> > struct intel_bios_encoder_data *devdata;
>> > @@ -1451,7 +1559,7 @@ parse_compression_parameters(struct drm_i915_private *i915,
>> > if (i915->vbt.version < 198)
>> > return;
>> >
>> > - params = find_section(bdb, BDB_COMPRESSION_PARAMETERS);
>> > + params = find_section(i915, BDB_COMPRESSION_PARAMETERS);
>> > if (params) {
>> > /* Sanity checks */
>> > if (params->entry_size != sizeof(params->data[0])) {
>> > @@ -2086,8 +2194,7 @@ static void parse_ddi_ports(struct drm_i915_private *i915)
>> > }
>> >
>> > static void
>> > -parse_general_definitions(struct drm_i915_private *i915,
>> > - const struct bdb_header *bdb)
>> > +parse_general_definitions(struct drm_i915_private *i915)
>> > {
>> > const struct bdb_general_definitions *defs;
>> > struct intel_bios_encoder_data *devdata;
>> > @@ -2097,7 +2204,7 @@ parse_general_definitions(struct drm_i915_private *i915,
>> > u16 block_size;
>> > int bus_pin;
>> >
>> > - defs = find_section(bdb, BDB_GENERAL_DEFINITIONS);
>> > + defs = find_section(i915, BDB_GENERAL_DEFINITIONS);
>> > if (!defs) {
>> > drm_dbg_kms(&i915->drm,
>> > "No general definition block is found, no devices defined.\n");
>> > @@ -2466,6 +2573,7 @@ void intel_bios_init(struct drm_i915_private *i915)
>> > const struct bdb_header *bdb;
>> >
>> > INIT_LIST_HEAD(&i915->vbt.display_devices);
>> > + INIT_LIST_HEAD(&i915->vbt.bdb_blocks);
>> >
>> > if (!HAS_DISPLAY(i915)) {
>> > drm_dbg_kms(&i915->drm,
>> > @@ -2499,22 +2607,24 @@ void intel_bios_init(struct drm_i915_private *i915)
>> > "VBT signature \"%.*s\", BDB version %d\n",
>> > (int)sizeof(vbt->signature), vbt->signature, i915->vbt.version);
>> >
>> > + init_bdb_blocks(i915, bdb);
>> > +
>> > /* Grab useful general definitions */
>> > - parse_general_features(i915, bdb);
>> > - parse_general_definitions(i915, bdb);
>> > - parse_panel_options(i915, bdb);
>> > + parse_general_features(i915);
>> > + parse_general_definitions(i915);
>> > + parse_panel_options(i915);
>> > parse_panel_dtd(i915, bdb);
>> > - parse_lfp_backlight(i915, bdb);
>> > - parse_sdvo_panel_data(i915, bdb);
>> > - parse_driver_features(i915, bdb);
>> > - parse_power_conservation_features(i915, bdb);
>> > - parse_edp(i915, bdb);
>> > - parse_psr(i915, bdb);
>> > - parse_mipi_config(i915, bdb);
>> > - parse_mipi_sequence(i915, bdb);
>> > + parse_lfp_backlight(i915);
>> > + parse_sdvo_panel_data(i915);
>> > + parse_driver_features(i915);
>> > + parse_power_conservation_features(i915);
>> > + parse_edp(i915);
>> > + parse_psr(i915);
>> > + parse_mipi_config(i915);
>> > + parse_mipi_sequence(i915);
>> >
>> > /* Depends on child device list */
>> > - parse_compression_parameters(i915, bdb);
>> > + parse_compression_parameters(i915);
>> >
>> > out:
>> > if (!vbt) {
>> > @@ -2536,14 +2646,20 @@ void intel_bios_init(struct drm_i915_private *i915)
>> > */
>> > void intel_bios_driver_remove(struct drm_i915_private *i915)
>> > {
>> > - struct intel_bios_encoder_data *devdata, *n;
>> > + struct intel_bios_encoder_data *devdata, *nd;
>> > + struct bdb_block_entry *entry, *ne;
>> >
>> > - list_for_each_entry_safe(devdata, n, &i915->vbt.display_devices, node) {
>> > + list_for_each_entry_safe(devdata, nd, &i915->vbt.display_devices, node) {
>> > list_del(&devdata->node);
>> > kfree(devdata->dsc);
>> > kfree(devdata);
>> > }
>> >
>> > + list_for_each_entry_safe(entry, ne, &i915->vbt.bdb_blocks, node) {
>> > + list_del(&entry->node);
>> > + kfree(entry);
>> > + }
>> > +
>> > kfree(i915->vbt.sdvo_lvds_vbt_mode);
>> > i915->vbt.sdvo_lvds_vbt_mode = NULL;
>> > kfree(i915->vbt.lfp_lvds_vbt_mode);
>> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>> > index 06e7c2802c5e..9274417cd87a 100644
>> > --- a/drivers/gpu/drm/i915/i915_drv.h
>> > +++ b/drivers/gpu/drm/i915/i915_drv.h
>> > @@ -380,6 +380,7 @@ struct intel_vbt_data {
>> > int crt_ddc_pin;
>> >
>> > struct list_head display_devices;
>> > + struct list_head bdb_blocks;
>> >
>> > struct intel_bios_encoder_data *ports[I915_MAX_PORTS]; /* Non-NULL if port present. */
>> > struct sdvo_device_mapping sdvo_mappings[2];
>>
>> --
>> Jani Nikula, Intel Open Source Graphics Center
--
Jani Nikula, Intel Open Source Graphics Center
