On 3/20/2020 2:46 AM, alvinx.zhang@intel.com wrote:
> From: Alvin Zhang <alvinx.zhang@intel.com>
>
> Implement device detection and loading.
> Add igc driver guid docs.
>
> Signed-off-by: Alvin Zhang <alvinx.zhang@intel.com>
>
> v2: Update release note. Modify codes according to comments
<...>
> @@ -0,0 +1,39 @@
> +.. SPDX-License-Identifier: BSD-3-Clause
> + Copyright(c) 2016 Intel Corporation.
Is the copyright date '2016' correct? If so you can update it as 2016-2020. This
comment is for all files.
> +
> +IGC Poll Mode Driver
> +======================
> +
> +The IGC PMD (librte_pmd_igc) provides poll mode driver support for
> +Foxville I225 Series Network Adapters.
Can you please provide some official links to the product? As much as possible
information about device is good.
<...>
> @@ -56,11 +56,16 @@ New Features
> Also, make sure to start the actual text at the margin.
> =========================================================
>
> -* **Updated Mellanox mlx5 driver.**
> + * **Updated Mellanox mlx5 driver.**
>
> - Updated Mellanox mlx5 driver with new features and improvements, including:
> + Updated Mellanox mlx5 driver with new features and improvements, including:
>
> - * Added support for matching on IPv4 Time To Live and IPv6 Hop Limit.
> + * Added support for matching on IPv4 Time To Live and IPv6 Hop Limit.
Above looks changed by mistake...
> +
> + * **Added a new driver for Intel Foxville I225 devices.**
> +
> + Added the new ``igc`` net driver for Intel Foxville I225 devices. See the
> + :doc:`../nics/igc` NIC guide for more details on this new driver.
>
>
> Removed Items
> diff --git a/drivers/net/Makefile b/drivers/net/Makefile
> index 4a7f155..b57841d 100644
> --- a/drivers/net/Makefile
> +++ b/drivers/net/Makefile
> @@ -61,6 +61,7 @@ DIRS-$(CONFIG_RTE_LIBRTE_THUNDERX_NICVF_PMD) += thunderx
> DIRS-$(CONFIG_RTE_LIBRTE_VDEV_NETVSC_PMD) += vdev_netvsc
> DIRS-$(CONFIG_RTE_LIBRTE_VIRTIO_PMD) += virtio
> DIRS-$(CONFIG_RTE_LIBRTE_VMXNET3_PMD) += vmxnet3
> +DIRS-$(CONFIG_RTE_LIBRTE_IGC_PMD) += igc
Can you please add it alphabetically sorted?
<...>
> +static int
> +eth_igc_dev_init(struct rte_eth_dev *dev)
> +{
> + struct rte_pci_device *pci_dev = RTE_ETH_DEV_TO_PCI(dev);
> +
> + PMD_INIT_FUNC_TRACE();
> + dev->dev_ops = ð_igc_ops;
> +
> + /*
> + * for secondary processes, we don't initialize any further as primary
> + * has already done this work. Only check we don't need a different
> + * RX function.
> + */
> + if (rte_eal_process_type() != RTE_PROC_PRIMARY)
> + return 0;
> +
> + rte_eth_copy_pci_info(dev, pci_dev);
This shouldn't be required, since it is done by
'rte_eth_dev_pci_generic_probe()' just before this funtion
('eth_igc_dev_init()') called.
> +
> + dev->data->mac_addrs = rte_zmalloc("igc",
> + RTE_ETHER_ADDR_LEN, 0);
> + if (dev->data->mac_addrs == NULL) {
> + PMD_INIT_LOG(ERR, "Failed to allocate %d bytes needed to "
> + "store MAC addresses", RTE_ETHER_ADDR_LEN);
> + return -ENOMEM;
> + }
> +
> + /* Pass the information to the rte_eth_dev_close() that it should also
> + * release the private port resources.
> + */
> + dev->data->dev_flags |= RTE_ETH_DEV_CLOSE_REMOVE;
> +
> + PMD_INIT_LOG(DEBUG, "port_id %d vendorID=0x%x deviceID=0x%x",
> + dev->data->port_id, pci_dev->id.vendor_id,
> + pci_dev->id.device_id);
> +
> + return 0;
> +}
> +
> +static int
> +eth_igc_dev_uninit(__rte_unused struct rte_eth_dev *eth_dev)
> +{
> + PMD_INIT_FUNC_TRACE();
> +
> + if (rte_eal_process_type() != RTE_PROC_PRIMARY)
> + return -EPERM;
It shouldn't return error for secondary. 'rte_eth_dev_release_port()' has
already process type in it, so returning '0' should work better which will cause
some process specific variables cleared.
<...>
> @@ -0,0 +1,21 @@
> +/* SPDX-License-Identifier: BSD-3-Clause
> + * Copyright(c) 2020 Intel Corporation
> + */
> +
> +#include "igc_logs.h"
> +#include "rte_common.h"
'rte_common.h' should be included with '<>', #include <rte_common.h>
> +
> +/* declared as extern in igc_logs.h */
> +int igc_logtype_init = -1;
> +int igc_logtype_driver = -1;
I guess no need to set initial values for these, by default '0' will work fine
for below logic.
<...>
> @@ -0,0 +1,3 @@
> +DPDK_20.0.1 {
This release it become "DPDK_20.0.2", although it doesn't matter for the PMD at
all, good to be consistent.
> + local: *;
> +};
> diff --git a/drivers/net/meson.build b/drivers/net/meson.build
> index b0ea8fe..7d0ae3b 100644
> --- a/drivers/net/meson.build
> +++ b/drivers/net/meson.build
> @@ -49,6 +49,7 @@ drivers = ['af_packet',
> 'vhost',
> 'virtio',
> 'vmxnet3',
> + 'igc',
Can you please add it alphabetically sorted?
@@ -704,6 +704,13 @@ F: drivers/net/ipn3ke/
F: doc/guides/nics/ipn3ke.rst
F: doc/guides/nics/features/ipn3ke.ini
+Intel igc
+M: Alvin Zhang <alvinx.zhang@intel.com>
+T: git://dpdk.org/next/dpdk-next-net-intel
+F: drivers/net/igc/
+F: doc/guides/nics/igc.rst
+F: doc/guides/nics/features/igc.ini
+
Marvell mvpp2
M: Tomasz Duszynski <tdu@semihalf.com>
M: Liron Himi <lironh@marvell.com>
@@ -283,6 +283,13 @@ CONFIG_RTE_LIBRTE_E1000_DEBUG_TX_FREE=n
CONFIG_RTE_LIBRTE_E1000_PF_DISABLE_STRIP_CRC=n
#
+# Compile burst-oriented IGC PMD drivers
+#
+CONFIG_RTE_LIBRTE_IGC_PMD=y
+CONFIG_RTE_LIBRTE_IGC_DEBUG_RX=n
+CONFIG_RTE_LIBRTE_IGC_DEBUG_TX=n
+
+#
# Compile burst-oriented HINIC PMD driver
#
CONFIG_RTE_LIBRTE_HINIC_PMD=n
new file mode 100644
@@ -0,0 +1,8 @@
+; Supported features of the 'igc' network poll mode driver.
+;
+; Refer to default.ini for the full list of available PMD features.
+;
+[Features]
+Linux UIO = Y
+Linux VFIO = Y
+x86-64 = Y
new file mode 100644
@@ -0,0 +1,39 @@
+.. SPDX-License-Identifier: BSD-3-Clause
+ Copyright(c) 2016 Intel Corporation.
+
+IGC Poll Mode Driver
+======================
+
+The IGC PMD (librte_pmd_igc) provides poll mode driver support for
+Foxville I225 Series Network Adapters.
+
+
+Config File Options
+~~~~~~~~~~~~~~~~~~~
+
+The following options can be modified in the ``config`` file.
+Please note that enabling debugging options may affect system performance.
+
+- ``CONFIG_RTE_LIBRTE_IGC_PMD`` (default ``y``)
+
+ Toggle compilation of the ``librte_pmd_igc`` driver.
+
+- ``CONFIG_RTE_LIBRTE_IGC_DEBUG_*`` (default ``n``)
+
+ Toggle display of generic debugging messages.
+
+
+Driver compilation and testing
+------------------------------
+
+Refer to the document :ref:`compiling and testing a PMD for a NIC <pmd_build_and_test>`
+for details.
+
+
+Supported Chipsets and NICs
+---------------------------
+
+Foxville LM (I225 LM): Client 2.5G LAN vPro Corporate
+Foxville V (I225 V): Client 2.5G LAN Consumer
+Foxville I (I225 I): Client 2.5G Industrial Temp
+Foxville V (I225 K): Client 2.5G LAN Consumer
@@ -32,6 +32,7 @@ Network Interface Controller Drivers
i40e
ice
igb
+ igc
ionic
ipn3ke
ixgbe
@@ -56,11 +56,16 @@ New Features
Also, make sure to start the actual text at the margin.
=========================================================
-* **Updated Mellanox mlx5 driver.**
+ * **Updated Mellanox mlx5 driver.**
- Updated Mellanox mlx5 driver with new features and improvements, including:
+ Updated Mellanox mlx5 driver with new features and improvements, including:
- * Added support for matching on IPv4 Time To Live and IPv6 Hop Limit.
+ * Added support for matching on IPv4 Time To Live and IPv6 Hop Limit.
+
+ * **Added a new driver for Intel Foxville I225 devices.**
+
+ Added the new ``igc`` net driver for Intel Foxville I225 devices. See the
+ :doc:`../nics/igc` NIC guide for more details on this new driver.
Removed Items
@@ -61,6 +61,7 @@ DIRS-$(CONFIG_RTE_LIBRTE_THUNDERX_NICVF_PMD) += thunderx
DIRS-$(CONFIG_RTE_LIBRTE_VDEV_NETVSC_PMD) += vdev_netvsc
DIRS-$(CONFIG_RTE_LIBRTE_VIRTIO_PMD) += virtio
DIRS-$(CONFIG_RTE_LIBRTE_VMXNET3_PMD) += vmxnet3
+DIRS-$(CONFIG_RTE_LIBRTE_IGC_PMD) += igc
ifeq ($(CONFIG_RTE_LIBRTE_KNI),y)
DIRS-$(CONFIG_RTE_LIBRTE_PMD_KNI) += kni
new file mode 100644
@@ -0,0 +1,25 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2010-2020 Intel Corporation
+
+include $(RTE_SDK)/mk/rte.vars.mk
+
+#
+# library name
+#
+LIB = librte_pmd_igc.a
+
+CFLAGS += -O3
+CFLAGS += $(WERROR_FLAGS)
+LDLIBS += -lrte_eal
+LDLIBS += -lrte_ethdev
+LDLIBS += -lrte_bus_pci
+
+EXPORT_MAP := rte_pmd_igc_version.map
+
+#
+# all source are stored in SRCS-y
+#
+SRCS-$(CONFIG_RTE_LIBRTE_IGC_PMD) += igc_logs.c
+SRCS-$(CONFIG_RTE_LIBRTE_IGC_PMD) += igc_ethdev.c
+
+include $(RTE_SDK)/mk/rte.lib.mk
new file mode 100644
@@ -0,0 +1,245 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2010-2020 Intel Corporation
+ */
+
+#include <rte_pci.h>
+#include <rte_bus_pci.h>
+#include <rte_ethdev_driver.h>
+#include <rte_ethdev_pci.h>
+
+#include "igc_logs.h"
+#include "igc_ethdev.h"
+
+#define IGC_INTEL_VENDOR_ID 0x8086
+#define IGC_DEV_ID_I225_LM 0x15F2
+#define IGC_DEV_ID_I225_V 0x15F3
+#define IGC_DEV_ID_I225_K 0x3100
+#define IGC_DEV_ID_I225_I 0x15F8
+#define IGC_DEV_ID_I220_V 0x15F7
+
+static const struct rte_pci_id pci_id_igc_map[] = {
+ { RTE_PCI_DEVICE(IGC_INTEL_VENDOR_ID, IGC_DEV_ID_I225_LM) },
+ { RTE_PCI_DEVICE(IGC_INTEL_VENDOR_ID, IGC_DEV_ID_I225_V) },
+ { RTE_PCI_DEVICE(IGC_INTEL_VENDOR_ID, IGC_DEV_ID_I225_I) },
+ { RTE_PCI_DEVICE(IGC_INTEL_VENDOR_ID, IGC_DEV_ID_I225_K) },
+ { .vendor_id = 0, /* sentinel */ },
+};
+
+static int eth_igc_configure(struct rte_eth_dev *dev);
+static int eth_igc_link_update(struct rte_eth_dev *dev, int wait_to_complete);
+static void eth_igc_stop(struct rte_eth_dev *dev);
+static int eth_igc_start(struct rte_eth_dev *dev);
+static void eth_igc_close(struct rte_eth_dev *dev);
+static int eth_igc_reset(struct rte_eth_dev *dev);
+static int eth_igc_promiscuous_enable(struct rte_eth_dev *dev);
+static int eth_igc_promiscuous_disable(struct rte_eth_dev *dev);
+static int eth_igc_infos_get(struct rte_eth_dev *dev,
+ struct rte_eth_dev_info *dev_info);
+static int
+eth_igc_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
+ uint16_t nb_rx_desc, unsigned int socket_id,
+ const struct rte_eth_rxconf *rx_conf,
+ struct rte_mempool *mb_pool);
+static int
+eth_igc_tx_queue_setup(struct rte_eth_dev *dev, uint16_t queue_idx,
+ uint16_t nb_desc, unsigned int socket_id,
+ const struct rte_eth_txconf *tx_conf);
+
+static const struct eth_dev_ops eth_igc_ops = {
+ .dev_configure = eth_igc_configure,
+ .link_update = eth_igc_link_update,
+ .dev_stop = eth_igc_stop,
+ .dev_start = eth_igc_start,
+ .dev_close = eth_igc_close,
+ .dev_reset = eth_igc_reset,
+ .promiscuous_enable = eth_igc_promiscuous_enable,
+ .promiscuous_disable = eth_igc_promiscuous_disable,
+ .dev_infos_get = eth_igc_infos_get,
+ .rx_queue_setup = eth_igc_rx_queue_setup,
+ .tx_queue_setup = eth_igc_tx_queue_setup,
+};
+
+static int
+eth_igc_configure(struct rte_eth_dev *dev)
+{
+ PMD_INIT_FUNC_TRACE();
+ RTE_SET_USED(dev);
+ return 0;
+}
+
+static int
+eth_igc_link_update(struct rte_eth_dev *dev, int wait_to_complete)
+{
+ PMD_INIT_FUNC_TRACE();
+ RTE_SET_USED(dev);
+ RTE_SET_USED(wait_to_complete);
+ return 0;
+}
+
+static void
+eth_igc_stop(struct rte_eth_dev *dev)
+{
+ PMD_INIT_FUNC_TRACE();
+ RTE_SET_USED(dev);
+}
+
+static int
+eth_igc_start(struct rte_eth_dev *dev)
+{
+ PMD_INIT_FUNC_TRACE();
+ RTE_SET_USED(dev);
+ return 0;
+}
+
+static void
+eth_igc_close(struct rte_eth_dev *dev)
+{
+ PMD_INIT_FUNC_TRACE();
+ RTE_SET_USED(dev);
+}
+
+static int
+eth_igc_dev_init(struct rte_eth_dev *dev)
+{
+ struct rte_pci_device *pci_dev = RTE_ETH_DEV_TO_PCI(dev);
+
+ PMD_INIT_FUNC_TRACE();
+ dev->dev_ops = ð_igc_ops;
+
+ /*
+ * for secondary processes, we don't initialize any further as primary
+ * has already done this work. Only check we don't need a different
+ * RX function.
+ */
+ if (rte_eal_process_type() != RTE_PROC_PRIMARY)
+ return 0;
+
+ rte_eth_copy_pci_info(dev, pci_dev);
+
+ dev->data->mac_addrs = rte_zmalloc("igc",
+ RTE_ETHER_ADDR_LEN, 0);
+ if (dev->data->mac_addrs == NULL) {
+ PMD_INIT_LOG(ERR, "Failed to allocate %d bytes needed to "
+ "store MAC addresses", RTE_ETHER_ADDR_LEN);
+ return -ENOMEM;
+ }
+
+ /* Pass the information to the rte_eth_dev_close() that it should also
+ * release the private port resources.
+ */
+ dev->data->dev_flags |= RTE_ETH_DEV_CLOSE_REMOVE;
+
+ PMD_INIT_LOG(DEBUG, "port_id %d vendorID=0x%x deviceID=0x%x",
+ dev->data->port_id, pci_dev->id.vendor_id,
+ pci_dev->id.device_id);
+
+ return 0;
+}
+
+static int
+eth_igc_dev_uninit(__rte_unused struct rte_eth_dev *eth_dev)
+{
+ PMD_INIT_FUNC_TRACE();
+
+ if (rte_eal_process_type() != RTE_PROC_PRIMARY)
+ return -EPERM;
+
+ eth_igc_close(eth_dev);
+ return 0;
+}
+
+static int
+eth_igc_reset(struct rte_eth_dev *dev)
+{
+ int ret;
+
+ PMD_INIT_FUNC_TRACE();
+
+ ret = eth_igc_dev_uninit(dev);
+ if (ret)
+ return ret;
+
+ return eth_igc_dev_init(dev);
+}
+
+static int
+eth_igc_promiscuous_enable(struct rte_eth_dev *dev)
+{
+ PMD_INIT_FUNC_TRACE();
+ RTE_SET_USED(dev);
+ return 0;
+}
+
+static int
+eth_igc_promiscuous_disable(struct rte_eth_dev *dev)
+{
+ PMD_INIT_FUNC_TRACE();
+ RTE_SET_USED(dev);
+ return 0;
+}
+
+static int
+eth_igc_infos_get(struct rte_eth_dev *dev, struct rte_eth_dev_info *dev_info)
+{
+ PMD_INIT_FUNC_TRACE();
+ RTE_SET_USED(dev);
+ dev_info->max_rx_queues = IGC_QUEUE_PAIRS_NUM;
+ dev_info->max_tx_queues = IGC_QUEUE_PAIRS_NUM;
+ return 0;
+}
+
+static int
+eth_igc_rx_queue_setup(struct rte_eth_dev *dev, uint16_t rx_queue_id,
+ uint16_t nb_rx_desc, unsigned int socket_id,
+ const struct rte_eth_rxconf *rx_conf,
+ struct rte_mempool *mb_pool)
+{
+ PMD_INIT_FUNC_TRACE();
+ RTE_SET_USED(dev);
+ RTE_SET_USED(rx_queue_id);
+ RTE_SET_USED(nb_rx_desc);
+ RTE_SET_USED(socket_id);
+ RTE_SET_USED(rx_conf);
+ RTE_SET_USED(mb_pool);
+ return 0;
+}
+
+static int
+eth_igc_tx_queue_setup(struct rte_eth_dev *dev, uint16_t queue_idx,
+ uint16_t nb_desc, unsigned int socket_id,
+ const struct rte_eth_txconf *tx_conf)
+{
+ PMD_INIT_FUNC_TRACE();
+ RTE_SET_USED(dev);
+ RTE_SET_USED(queue_idx);
+ RTE_SET_USED(nb_desc);
+ RTE_SET_USED(socket_id);
+ RTE_SET_USED(tx_conf);
+ return 0;
+}
+
+static int
+eth_igc_pci_probe(struct rte_pci_driver *pci_drv __rte_unused,
+ struct rte_pci_device *pci_dev)
+{
+ PMD_INIT_FUNC_TRACE();
+ return rte_eth_dev_pci_generic_probe(pci_dev, 0, eth_igc_dev_init);
+}
+
+static int
+eth_igc_pci_remove(struct rte_pci_device *pci_dev)
+{
+ PMD_INIT_FUNC_TRACE();
+ return rte_eth_dev_pci_generic_remove(pci_dev, eth_igc_dev_uninit);
+}
+
+static struct rte_pci_driver rte_igc_pmd = {
+ .id_table = pci_id_igc_map,
+ .drv_flags = RTE_PCI_DRV_NEED_MAPPING | RTE_PCI_DRV_INTR_LSC,
+ .probe = eth_igc_pci_probe,
+ .remove = eth_igc_pci_remove,
+};
+
+RTE_PMD_REGISTER_PCI(net_igc, rte_igc_pmd);
+RTE_PMD_REGISTER_PCI_TABLE(net_igc, pci_id_igc_map);
+RTE_PMD_REGISTER_KMOD_DEP(net_igc, "* igb_uio | uio_pci_generic | vfio-pci");
new file mode 100644
@@ -0,0 +1,18 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2010-2020 Intel Corporation
+ */
+
+#ifndef _IGC_ETHDEV_H_
+#define _IGC_ETHDEV_H_
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+#define IGC_QUEUE_PAIRS_NUM 4
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _IGC_ETHDEV_H_ */
new file mode 100644
@@ -0,0 +1,21 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2020 Intel Corporation
+ */
+
+#include "igc_logs.h"
+#include "rte_common.h"
+
+/* declared as extern in igc_logs.h */
+int igc_logtype_init = -1;
+int igc_logtype_driver = -1;
+
+RTE_INIT(igc_init_log)
+{
+ igc_logtype_init = rte_log_register("pmd.net.igc.init");
+ if (igc_logtype_init >= 0)
+ rte_log_set_level(igc_logtype_init, RTE_LOG_INFO);
+
+ igc_logtype_driver = rte_log_register("pmd.net.igc.driver");
+ if (igc_logtype_driver >= 0)
+ rte_log_set_level(igc_logtype_driver, RTE_LOG_INFO);
+}
new file mode 100644
@@ -0,0 +1,34 @@
+/* SPDX-License-Identifier: BSD-3-Clause
+ * Copyright(c) 2010-2020 Intel Corporation
+ */
+
+#ifndef _IGC_LOGS_H_
+#define _IGC_LOGS_H_
+
+#include <rte_log.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+extern int igc_logtype_init;
+extern int igc_logtype_driver;
+
+#define PMD_INIT_LOG(level, fmt, args...) \
+ rte_log(RTE_LOG_ ## level, igc_logtype_init, \
+ "%s(): " fmt "\n", __func__, ##args)
+
+#define PMD_INIT_FUNC_TRACE() PMD_INIT_LOG(DEBUG, " >>")
+
+#define PMD_DRV_LOG_RAW(level, fmt, args...) \
+ rte_log(RTE_LOG_ ## level, igc_logtype_driver, "%s(): " fmt, \
+ __func__, ## args)
+
+#define PMD_DRV_LOG(level, fmt, args...) \
+ PMD_DRV_LOG_RAW(level, fmt "\n", ## args)
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* _IGC_LOGS_H_ */
new file mode 100644
@@ -0,0 +1,7 @@
+# SPDX-License-Identifier: BSD-3-Clause
+# Copyright(c) 2020 Intel Corporation
+
+sources = files(
+ 'igc_logs.c',
+ 'igc_ethdev.c'
+)
new file mode 100644
@@ -0,0 +1,3 @@
+DPDK_20.0.1 {
+ local: *;
+};
@@ -49,6 +49,7 @@ drivers = ['af_packet',
'vhost',
'virtio',
'vmxnet3',
+ 'igc',
]
std_deps = ['ethdev', 'kvargs'] # 'ethdev' also pulls in mbuf, net, eal etc
std_deps += ['bus_pci'] # very many PMDs depend on PCI, so make std
@@ -184,6 +184,7 @@ _LDLIBS-$(CONFIG_RTE_LIBRTE_HNS3_PMD) += -lrte_pmd_hns3
_LDLIBS-$(CONFIG_RTE_LIBRTE_I40E_PMD) += -lrte_pmd_i40e
_LDLIBS-$(CONFIG_RTE_LIBRTE_IAVF_PMD) += -lrte_pmd_iavf
_LDLIBS-$(CONFIG_RTE_LIBRTE_ICE_PMD) += -lrte_pmd_ice
+_LDLIBS-$(CONFIG_RTE_LIBRTE_IGC_PMD) += -lrte_pmd_igc
IAVF-y := $(CONFIG_RTE_LIBRTE_IAVF_PMD)
ifeq ($(findstring y,$(IAVF-y)),y)
_LDLIBS-y += -lrte_common_iavf