src/net/netdev_settings.c - ipxe - Git at Google

 /*
  * Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
  *
  * This program is free software; you can redistribute it and/or
  * modify it under the terms of the GNU General Public License as
  * published by the Free Software Foundation; either version 2 of the
  * License, or any later version.
  *
  * This program is distributed in the hope that it will be useful, but
  * WITHOUT ANY WARRANTY; without even the implied warranty of
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  * General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  * 02110-1301, USA.
  *
  * You can also choose to distribute this program under the terms of
  * the Unmodified Binary Distribution Licence (as given in the file
  * COPYING.UBDL), provided that you have satisfied its requirements.
  */

 FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

 #include <string.h>
 #include <errno.h>
 #include <byteswap.h>
 #include <ipxe/dhcp.h>
 #include <ipxe/dhcpopts.h>
 #include <ipxe/settings.h>
 #include <ipxe/device.h>
 #include <ipxe/netdevice.h>
 #include <ipxe/init.h>

 /** @file
  *
  * Network device configuration settings
  *
  */

 /** Network device predefined settings */
 const struct setting mac_setting __setting ( SETTING_NETDEV, mac ) = {
 	.name = "mac",
 	.description = "MAC address",
 	.type = &setting_type_hex,
 };
 const struct setting hwaddr_setting __setting ( SETTING_NETDEV, hwaddr ) = {
 	.name = "hwaddr",
 	.description = "Hardware address",
 	.type = &setting_type_hex,
 };
 const struct setting bustype_setting __setting ( SETTING_NETDEV, bustype ) = {
 	.name = "bustype",
 	.description = "Bus type",
 	.type = &setting_type_string,
 };
 const struct setting busloc_setting __setting ( SETTING_NETDEV, busloc ) = {
 	.name = "busloc",
 	.description = "Bus location",
 	.type = &setting_type_uint32,
 };
 const struct setting busid_setting __setting ( SETTING_NETDEV, busid ) = {
 	.name = "busid",
 	.description = "Bus ID",
 	.type = &setting_type_hex,
 };
 const struct setting chip_setting __setting ( SETTING_NETDEV, chip ) = {
 	.name = "chip",
 	.description = "Chip",
 	.type = &setting_type_string,
 };
 const struct setting ifname_setting __setting ( SETTING_NETDEV, ifname ) = {
 	.name = "ifname",
 	.description = "Interface name",
 	.type = &setting_type_string,
 };
 const struct setting mtu_setting __setting ( SETTING_NETDEV, mtu ) = {
 	.name = "mtu",
 	.description = "MTU",
 	.type = &setting_type_int16,
 	.tag = DHCP_MTU,
 };

 /**
  * Store link-layer address setting
  *
  * @v netdev		Network device
  * @v data		Setting data, or NULL to clear setting
  * @v len		Length of setting data
  * @ret rc		Return status code
  */
 static int netdev_store_mac ( struct net_device *netdev,
 			      const void *data, size_t len ) {
 	struct ll_protocol *ll_protocol = netdev->ll_protocol;

 	/* Record new MAC address */
 	if ( data ) {
 		if ( len != netdev->ll_protocol->ll_addr_len )
 			return -EINVAL;
 		memcpy ( netdev->ll_addr, data, len );
 	} else {
 		/* Reset MAC address if clearing setting */
 		ll_protocol->init_addr ( netdev->hw_addr, netdev->ll_addr );
 	}

 	return 0;
 }

 /**
  * Fetch link-layer address setting
  *
  * @v netdev		Network device
  * @v data		Buffer to fill with setting data
  * @v len		Length of buffer
  * @ret len		Length of setting data, or negative error
  */
 static int netdev_fetch_mac ( struct net_device *netdev, void *data,
 			      size_t len ) {
 	size_t max_len = netdev->ll_protocol->ll_addr_len;

 	if ( len > max_len )
 		len = max_len;
 	memcpy ( data, netdev->ll_addr, len );
 	return max_len;
 }

 /**
  * Fetch hardware address setting
  *
  * @v netdev		Network device
  * @v data		Buffer to fill with setting data
  * @v len		Length of buffer
  * @ret len		Length of setting data, or negative error
  */
 static int netdev_fetch_hwaddr ( struct net_device *netdev, void *data,
 				 size_t len ) {
 	size_t max_len = netdev->ll_protocol->hw_addr_len;

 	if ( len > max_len )
 		len = max_len;
 	memcpy ( data, netdev->hw_addr, len );
 	return max_len;
 }

 /**
  * Fetch bus type setting
  *
  * @v netdev		Network device
  * @v data		Buffer to fill with setting data
  * @v len		Length of buffer
  * @ret len		Length of setting data, or negative error
  */
 static int netdev_fetch_bustype ( struct net_device *netdev, void *data,
 				  size_t len ) {
 	static const char *bustypes[] = {
 		[BUS_TYPE_PCI] = "PCI",
 		[BUS_TYPE_ISAPNP] = "ISAPNP",
 		[BUS_TYPE_EISA] = "EISA",
 		[BUS_TYPE_MCA] = "MCA",
 		[BUS_TYPE_ISA] = "ISA",
 		[BUS_TYPE_TAP] = "TAP",
 		[BUS_TYPE_EFI] = "EFI",
 		[BUS_TYPE_XEN] = "XEN",
 		[BUS_TYPE_HV] = "HV",
 		[BUS_TYPE_USB] = "USB",
 	};
 	struct device_description *desc = &netdev->dev->desc;
 	const char *bustype;

 	assert ( desc->bus_type < ( sizeof ( bustypes ) /
 				    sizeof ( bustypes[0] ) ) );
 	bustype = bustypes[desc->bus_type];
 	if ( ! bustype )
 		return -ENOENT;
 	strncpy ( data, bustype, len );
 	return strlen ( bustype );
 }

 /**
  * Fetch bus location setting
  *
  * @v netdev		Network device
  * @v data		Buffer to fill with setting data
  * @v len		Length of buffer
  * @ret len		Length of setting data, or negative error
  */
 static int netdev_fetch_busloc ( struct net_device *netdev, void *data,
 				 size_t len ) {
 	struct device_description *desc = &netdev->dev->desc;
 	uint32_t busloc;

 	busloc = cpu_to_be32 ( desc->location );
 	if ( len > sizeof ( busloc ) )
 		len = sizeof ( busloc );
 	memcpy ( data, &busloc, len );
 	return sizeof ( busloc );
 }

 /**
  * Fetch bus ID setting
  *
  * @v netdev		Network device
  * @v data		Buffer to fill with setting data
  * @v len		Length of buffer
  * @ret len		Length of setting data, or negative error
  */
 static int netdev_fetch_busid ( struct net_device *netdev, void *data,
 				size_t len ) {
 	struct device_description *desc = &netdev->dev->desc;
 	struct dhcp_netdev_desc dhcp_desc;

 	dhcp_desc.type = desc->bus_type;
 	dhcp_desc.vendor = htons ( desc->vendor );
 	dhcp_desc.device = htons ( desc->device );
 	if ( len > sizeof ( dhcp_desc ) )
 		len = sizeof ( dhcp_desc );
 	memcpy ( data, &dhcp_desc, len );
 	return sizeof ( dhcp_desc );
 }

 /**
  * Fetch chip setting
  *
  * @v netdev		Network device
  * @v data		Buffer to fill with setting data
  * @v len		Length of buffer
  * @ret len		Length of setting data, or negative error
  */
 static int netdev_fetch_chip ( struct net_device *netdev, void *data,
 			       size_t len ) {
 	const char *chip = netdev->dev->driver_name;

 	strncpy ( data, chip, len );
 	return strlen ( chip );
 }

 /**
  * Fetch ifname setting
  *
  * @v netdev		Network device
  * @v data		Buffer to fill with setting data
  * @v len		Length of buffer
  * @ret len		Length of setting data, or negative error
  */
 static int netdev_fetch_ifname ( struct net_device *netdev, void *data,
 				 size_t len ) {
 	const char *ifname = netdev->name;

 	strncpy ( data, ifname, len );
 	return strlen ( ifname );
 }

 /** A network device setting operation */
 struct netdev_setting_operation {
 	/** Setting */
 	const struct setting *setting;
 	/** Store setting (or NULL if not supported)
 	 *
 	 * @v netdev		Network device
 	 * @v data		Setting data, or NULL to clear setting
 	 * @v len		Length of setting data
 	 * @ret rc		Return status code
 	 */
 	int ( * store ) ( struct net_device *netdev, const void *data,
 			  size_t len );
 	/** Fetch setting
 	 *
 	 * @v netdev		Network device
 	 * @v data		Buffer to fill with setting data
 	 * @v len		Length of buffer
 	 * @ret len		Length of setting data, or negative error
 	 */
 	int ( * fetch ) ( struct net_device *netdev, void *data, size_t len );
 };

 /** Network device settings */
 static struct netdev_setting_operation netdev_setting_operations[] = {
 	{ &mac_setting, netdev_store_mac, netdev_fetch_mac },
 	{ &hwaddr_setting, NULL, netdev_fetch_hwaddr },
 	{ &bustype_setting, NULL, netdev_fetch_bustype },
 	{ &busloc_setting, NULL, netdev_fetch_busloc },
 	{ &busid_setting, NULL, netdev_fetch_busid },
 	{ &chip_setting, NULL, netdev_fetch_chip },
 	{ &ifname_setting, NULL, netdev_fetch_ifname },
 };

 /**
  * Store value of network device setting
  *
  * @v settings		Settings block
  * @v setting		Setting to store
  * @v data		Setting data, or NULL to clear setting
  * @v len		Length of setting data
  * @ret rc		Return status code
  */
 static int netdev_store ( struct settings *settings,
 			  const struct setting *setting,
 			  const void *data, size_t len ) {
 	struct net_device *netdev = container_of ( settings, struct net_device,
 						   settings.settings );
 	struct netdev_setting_operation *op;
 	unsigned int i;

 	/* Handle network device-specific settings */
 	for ( i = 0 ; i < ( sizeof ( netdev_setting_operations ) /
 			    sizeof ( netdev_setting_operations[0] ) ) ; i++ ) {
 		op = &netdev_setting_operations[i];
 		if ( setting_cmp ( setting, op->setting ) == 0 ) {
 			if ( op->store ) {
 				return op->store ( netdev, data, len );
 			} else {
 				return -ENOTSUP;
 			}
 		}
 	}

 	return generic_settings_store ( settings, setting, data, len );
 }

 /**
  * Fetch value of network device setting
  *
  * @v settings		Settings block
  * @v setting		Setting to fetch
  * @v data		Buffer to fill with setting data
  * @v len		Length of buffer
  * @ret len		Length of setting data, or negative error
  */
 static int netdev_fetch ( struct settings *settings, struct setting *setting,
 			  void *data, size_t len ) {
 	struct net_device *netdev = container_of ( settings, struct net_device,
 						   settings.settings );
 	struct netdev_setting_operation *op;
 	unsigned int i;

 	/* Handle network device-specific settings */
 	for ( i = 0 ; i < ( sizeof ( netdev_setting_operations ) /
 			    sizeof ( netdev_setting_operations[0] ) ) ; i++ ) {
 		op = &netdev_setting_operations[i];
 		if ( setting_cmp ( setting, op->setting ) == 0 )
 			return op->fetch ( netdev, data, len );
 	}

 	return generic_settings_fetch ( settings, setting, data, len );
 }

 /**
  * Clear network device settings
  *
  * @v settings		Settings block
  */
 static void netdev_clear ( struct settings *settings ) {
 	generic_settings_clear ( settings );
 }

 /** Network device configuration settings operations */
 struct settings_operations netdev_settings_operations = {
 	.store = netdev_store,
 	.fetch = netdev_fetch,
 	.clear = netdev_clear,
 };

 /**
  * Redirect "netX" settings block
  *
  * @v settings		Settings block
  * @ret settings	Underlying settings block
  */
 static struct settings * netdev_redirect ( struct settings *settings ) {
 	struct net_device *netdev;

 	/* Redirect to most recently opened network device */
 	netdev = last_opened_netdev();
 	if ( netdev ) {
 		return netdev_settings ( netdev );
 	} else {
 		return settings;
 	}
 }

 /** "netX" settings operations */
 static struct settings_operations netdev_redirect_settings_operations = {
 	.redirect = netdev_redirect,
 };

 /** "netX" settings */
 static struct settings netdev_redirect_settings = {
 	.refcnt = NULL,
 	.siblings = LIST_HEAD_INIT ( netdev_redirect_settings.siblings ),
 	.children = LIST_HEAD_INIT ( netdev_redirect_settings.children ),
 	.op = &netdev_redirect_settings_operations,
 };

 /** Initialise "netX" settings */
 static void netdev_redirect_settings_init ( void ) {
 	int rc;

 	if ( ( rc = register_settings ( &netdev_redirect_settings, NULL,
 					"netX" ) ) != 0 ) {
 		DBG ( "Could not register netX settings: %s\n",
 		      strerror ( rc ) );
 		return;
 	}
 }

 /** "netX" settings initialiser */
 struct init_fn netdev_redirect_settings_init_fn __init_fn ( INIT_LATE ) = {
 	.initialise = netdev_redirect_settings_init,
 };

 /**
  * Apply network device settings
  *
  * @ret rc		Return status code
  */
 static int apply_netdev_settings ( void ) {
 	struct net_device *netdev;
 	struct settings *settings;
 	struct ll_protocol *ll_protocol;
 	size_t max_mtu;
 	size_t old_mtu;
 	size_t mtu;
 	int rc;

 	/* Process settings for each network device */
 	for_each_netdev ( netdev ) {

 		/* Get network device settings */
 		settings = netdev_settings ( netdev );

 		/* Get MTU */
 		mtu = fetch_uintz_setting ( settings, &mtu_setting );

 		/* Do nothing unless MTU is specified */
 		if ( ! mtu )
 			continue;

 		/* Limit MTU to maximum supported by hardware */
 		ll_protocol = netdev->ll_protocol;
 		max_mtu = ( netdev->max_pkt_len - ll_protocol->ll_header_len );
 		if ( mtu > max_mtu ) {
 			DBGC ( netdev, "NETDEV %s cannot support MTU %zd (max "
 			       "%zd)\n", netdev->name, mtu, max_mtu );
 			mtu = max_mtu;
 		}

 		/* Update maximum packet length */
 		old_mtu = netdev->mtu;
 		netdev->mtu = mtu;
 		if ( mtu != old_mtu ) {
 			DBGC ( netdev, "NETDEV %s MTU is %zd\n",
 			       netdev->name, mtu );
 		}

 		/* Close and reopen network device if MTU has increased */
 		if ( netdev_is_open ( netdev ) && ( mtu > old_mtu ) ) {
 			netdev_close ( netdev );
 			if ( ( rc = netdev_open ( netdev ) ) != 0 ) {
 				DBGC ( netdev, "NETDEV %s could not reopen: "
 				       "%s\n", netdev->name, strerror ( rc ) );
 				return rc;
 			}
 		}
 	}

 	return 0;
 }

 /** Network device settings applicator */
 struct settings_applicator netdev_applicator __settings_applicator = {
 	.apply = apply_netdev_settings,
 };
	/*
	* Copyright (C) 2008 Michael Brown <mbrown@fensystems.co.uk>.
	*
	* This program is free software; you can redistribute it and/or
	* modify it under the terms of the GNU General Public License as
	* published by the Free Software Foundation; either version 2 of the
	* License, or any later version.
	*
	* This program is distributed in the hope that it will be useful, but
	* WITHOUT ANY WARRANTY; without even the implied warranty of
	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	* General Public License for more details.
	*
	* You should have received a copy of the GNU General Public License
	* along with this program; if not, write to the Free Software
	* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
	* 02110-1301, USA.
	*
	* You can also choose to distribute this program under the terms of
	* the Unmodified Binary Distribution Licence (as given in the file
	* COPYING.UBDL), provided that you have satisfied its requirements.
	*/

	FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );

	#include <string.h>
	#include <errno.h>
	#include <byteswap.h>
	#include <ipxe/dhcp.h>
	#include <ipxe/dhcpopts.h>
	#include <ipxe/settings.h>
	#include <ipxe/device.h>
	#include <ipxe/netdevice.h>
	#include <ipxe/init.h>

	/** @file
	*
	* Network device configuration settings
	*
	*/

	/** Network device predefined settings */
	const struct setting mac_setting __setting ( SETTING_NETDEV, mac ) = {
	.name = "mac",
	.description = "MAC address",
	.type = &setting_type_hex,
	};
	const struct setting hwaddr_setting __setting ( SETTING_NETDEV, hwaddr ) = {
	.name = "hwaddr",
	.description = "Hardware address",
	.type = &setting_type_hex,
	};
	const struct setting bustype_setting __setting ( SETTING_NETDEV, bustype ) = {
	.name = "bustype",
	.description = "Bus type",
	.type = &setting_type_string,
	};
	const struct setting busloc_setting __setting ( SETTING_NETDEV, busloc ) = {
	.name = "busloc",
	.description = "Bus location",
	.type = &setting_type_uint32,
	};
	const struct setting busid_setting __setting ( SETTING_NETDEV, busid ) = {
	.name = "busid",
	.description = "Bus ID",
	.type = &setting_type_hex,
	};
	const struct setting chip_setting __setting ( SETTING_NETDEV, chip ) = {
	.name = "chip",
	.description = "Chip",
	.type = &setting_type_string,
	};
	const struct setting ifname_setting __setting ( SETTING_NETDEV, ifname ) = {
	.name = "ifname",
	.description = "Interface name",
	.type = &setting_type_string,
	};
	const struct setting mtu_setting __setting ( SETTING_NETDEV, mtu ) = {
	.name = "mtu",
	.description = "MTU",
	.type = &setting_type_int16,
	.tag = DHCP_MTU,
	};

	/**
	* Store link-layer address setting
	*
	* @v netdev Network device
	* @v data Setting data, or NULL to clear setting
	* @v len Length of setting data
	* @ret rc Return status code
	*/
	static int netdev_store_mac ( struct net_device *netdev,
	const void *data, size_t len ) {
	struct ll_protocol *ll_protocol = netdev->ll_protocol;

	/* Record new MAC address */
	if ( data ) {
	if ( len != netdev->ll_protocol->ll_addr_len )
	return -EINVAL;
	memcpy ( netdev->ll_addr, data, len );
	} else {
	/* Reset MAC address if clearing setting */
	ll_protocol->init_addr ( netdev->hw_addr, netdev->ll_addr );
	}

	return 0;
	}

	/**
	* Fetch link-layer address setting
	*
	* @v netdev Network device
	* @v data Buffer to fill with setting data
	* @v len Length of buffer
	* @ret len Length of setting data, or negative error
	*/
	static int netdev_fetch_mac ( struct net_device netdev, void data,
	size_t len ) {
	size_t max_len = netdev->ll_protocol->ll_addr_len;

	if ( len > max_len )
	len = max_len;
	memcpy ( data, netdev->ll_addr, len );
	return max_len;
	}

	/**
	* Fetch hardware address setting
	*
	* @v netdev Network device
	* @v data Buffer to fill with setting data
	* @v len Length of buffer
	* @ret len Length of setting data, or negative error
	*/
	static int netdev_fetch_hwaddr ( struct net_device netdev, void data,
	size_t len ) {
	size_t max_len = netdev->ll_protocol->hw_addr_len;

	if ( len > max_len )
	len = max_len;
	memcpy ( data, netdev->hw_addr, len );
	return max_len;
	}

	/**
	* Fetch bus type setting
	*
	* @v netdev Network device
	* @v data Buffer to fill with setting data
	* @v len Length of buffer
	* @ret len Length of setting data, or negative error
	*/
	static int netdev_fetch_bustype ( struct net_device netdev, void data,
	size_t len ) {
	static const char *bustypes[] = {
	[BUS_TYPE_PCI] = "PCI",
	[BUS_TYPE_ISAPNP] = "ISAPNP",
	[BUS_TYPE_EISA] = "EISA",
	[BUS_TYPE_MCA] = "MCA",
	[BUS_TYPE_ISA] = "ISA",
	[BUS_TYPE_TAP] = "TAP",
	[BUS_TYPE_EFI] = "EFI",
	[BUS_TYPE_XEN] = "XEN",
	[BUS_TYPE_HV] = "HV",
	[BUS_TYPE_USB] = "USB",
	};
	struct device_description *desc = &netdev->dev->desc;
	const char *bustype;

	assert ( desc->bus_type < ( sizeof ( bustypes ) /
	sizeof ( bustypes[0] ) ) );
	bustype = bustypes[desc->bus_type];
	if ( ! bustype )
	return -ENOENT;
	strncpy ( data, bustype, len );
	return strlen ( bustype );
	}

	/**
	* Fetch bus location setting
	*
	* @v netdev Network device
	* @v data Buffer to fill with setting data
	* @v len Length of buffer
	* @ret len Length of setting data, or negative error
	*/
	static int netdev_fetch_busloc ( struct net_device netdev, void data,
	size_t len ) {
	struct device_description *desc = &netdev->dev->desc;
	uint32_t busloc;

	busloc = cpu_to_be32 ( desc->location );
	if ( len > sizeof ( busloc ) )
	len = sizeof ( busloc );
	memcpy ( data, &busloc, len );
	return sizeof ( busloc );
	}

	/**
	* Fetch bus ID setting
	*
	* @v netdev Network device
	* @v data Buffer to fill with setting data
	* @v len Length of buffer
	* @ret len Length of setting data, or negative error
	*/
	static int netdev_fetch_busid ( struct net_device netdev, void data,
	size_t len ) {
	struct device_description *desc = &netdev->dev->desc;
	struct dhcp_netdev_desc dhcp_desc;

	dhcp_desc.type = desc->bus_type;
	dhcp_desc.vendor = htons ( desc->vendor );
	dhcp_desc.device = htons ( desc->device );
	if ( len > sizeof ( dhcp_desc ) )
	len = sizeof ( dhcp_desc );
	memcpy ( data, &dhcp_desc, len );
	return sizeof ( dhcp_desc );
	}

	/**
	* Fetch chip setting
	*
	* @v netdev Network device
	* @v data Buffer to fill with setting data
	* @v len Length of buffer
	* @ret len Length of setting data, or negative error
	*/
	static int netdev_fetch_chip ( struct net_device netdev, void data,
	size_t len ) {
	const char *chip = netdev->dev->driver_name;

	strncpy ( data, chip, len );
	return strlen ( chip );
	}

	/**
	* Fetch ifname setting
	*
	* @v netdev Network device
	* @v data Buffer to fill with setting data
	* @v len Length of buffer
	* @ret len Length of setting data, or negative error
	*/
	static int netdev_fetch_ifname ( struct net_device netdev, void data,
	size_t len ) {
	const char *ifname = netdev->name;

	strncpy ( data, ifname, len );
	return strlen ( ifname );
	}

	/** A network device setting operation */
	struct netdev_setting_operation {
	/** Setting */
	const struct setting *setting;
	/** Store setting (or NULL if not supported)
	*
	* @v netdev Network device
	* @v data Setting data, or NULL to clear setting
	* @v len Length of setting data
	* @ret rc Return status code
	*/
	int ( * store ) ( struct net_device netdev, const void data,
	size_t len );
	/** Fetch setting
	*
	* @v netdev Network device
	* @v data Buffer to fill with setting data
	* @v len Length of buffer
	* @ret len Length of setting data, or negative error
	*/
	int ( * fetch ) ( struct net_device netdev, void data, size_t len );
	};

	/** Network device settings */
	static struct netdev_setting_operation netdev_setting_operations[] = {
	{ &mac_setting, netdev_store_mac, netdev_fetch_mac },
	{ &hwaddr_setting, NULL, netdev_fetch_hwaddr },
	{ &bustype_setting, NULL, netdev_fetch_bustype },
	{ &busloc_setting, NULL, netdev_fetch_busloc },
	{ &busid_setting, NULL, netdev_fetch_busid },
	{ &chip_setting, NULL, netdev_fetch_chip },
	{ &ifname_setting, NULL, netdev_fetch_ifname },
	};

	/**
	* Store value of network device setting
	*
	* @v settings Settings block
	* @v setting Setting to store
	* @v data Setting data, or NULL to clear setting
	* @v len Length of setting data
	* @ret rc Return status code
	*/
	static int netdev_store ( struct settings *settings,
	const struct setting *setting,
	const void *data, size_t len ) {
	struct net_device *netdev = container_of ( settings, struct net_device,
	settings.settings );
	struct netdev_setting_operation *op;
	unsigned int i;

	/* Handle network device-specific settings */
	for ( i = 0 ; i < ( sizeof ( netdev_setting_operations ) /
	sizeof ( netdev_setting_operations[0] ) ) ; i++ ) {
	op = &netdev_setting_operations[i];
	if ( setting_cmp ( setting, op->setting ) == 0 ) {
	if ( op->store ) {
	return op->store ( netdev, data, len );
	} else {
	return -ENOTSUP;
	}
	}
	}

	return generic_settings_store ( settings, setting, data, len );
	}

	/**
	* Fetch value of network device setting
	*
	* @v settings Settings block
	* @v setting Setting to fetch
	* @v data Buffer to fill with setting data
	* @v len Length of buffer
	* @ret len Length of setting data, or negative error
	*/
	static int netdev_fetch ( struct settings settings, struct setting setting,
	void *data, size_t len ) {
	struct net_device *netdev = container_of ( settings, struct net_device,
	settings.settings );
	struct netdev_setting_operation *op;
	unsigned int i;

	/* Handle network device-specific settings */
	for ( i = 0 ; i < ( sizeof ( netdev_setting_operations ) /
	sizeof ( netdev_setting_operations[0] ) ) ; i++ ) {
	op = &netdev_setting_operations[i];
	if ( setting_cmp ( setting, op->setting ) == 0 )
	return op->fetch ( netdev, data, len );
	}

	return generic_settings_fetch ( settings, setting, data, len );
	}

	/**
	* Clear network device settings
	*
	* @v settings Settings block
	*/
	static void netdev_clear ( struct settings *settings ) {
	generic_settings_clear ( settings );
	}

	/** Network device configuration settings operations */
	struct settings_operations netdev_settings_operations = {
	.store = netdev_store,
	.fetch = netdev_fetch,
	.clear = netdev_clear,
	};

	/**
	* Redirect "netX" settings block
	*
	* @v settings Settings block
	* @ret settings Underlying settings block
	*/
	static struct settings * netdev_redirect ( struct settings *settings ) {
	struct net_device *netdev;

	/* Redirect to most recently opened network device */
	netdev = last_opened_netdev();
	if ( netdev ) {
	return netdev_settings ( netdev );
	} else {
	return settings;
	}
	}

	/** "netX" settings operations */
	static struct settings_operations netdev_redirect_settings_operations = {
	.redirect = netdev_redirect,
	};

	/** "netX" settings */
	static struct settings netdev_redirect_settings = {
	.refcnt = NULL,
	.siblings = LIST_HEAD_INIT ( netdev_redirect_settings.siblings ),
	.children = LIST_HEAD_INIT ( netdev_redirect_settings.children ),
	.op = &netdev_redirect_settings_operations,
	};

	/** Initialise "netX" settings */
	static void netdev_redirect_settings_init ( void ) {
	int rc;

	if ( ( rc = register_settings ( &netdev_redirect_settings, NULL,
	"netX" ) ) != 0 ) {
	DBG ( "Could not register netX settings: %s\n",
	strerror ( rc ) );
	return;
	}
	}

	/** "netX" settings initialiser */
	struct init_fn netdev_redirect_settings_init_fn __init_fn ( INIT_LATE ) = {
	.initialise = netdev_redirect_settings_init,
	};

	/**
	* Apply network device settings
	*
	* @ret rc Return status code
	*/
	static int apply_netdev_settings ( void ) {
	struct net_device *netdev;
	struct settings *settings;
	struct ll_protocol *ll_protocol;
	size_t max_mtu;
	size_t old_mtu;
	size_t mtu;
	int rc;

	/* Process settings for each network device */
	for_each_netdev ( netdev ) {

	/* Get network device settings */
	settings = netdev_settings ( netdev );

	/* Get MTU */
	mtu = fetch_uintz_setting ( settings, &mtu_setting );

	/* Do nothing unless MTU is specified */
	if ( ! mtu )
	continue;

	/* Limit MTU to maximum supported by hardware */
	ll_protocol = netdev->ll_protocol;
	max_mtu = ( netdev->max_pkt_len - ll_protocol->ll_header_len );
	if ( mtu > max_mtu ) {
	DBGC ( netdev, "NETDEV %s cannot support MTU %zd (max "
	"%zd)\n", netdev->name, mtu, max_mtu );
	mtu = max_mtu;
	}

	/* Update maximum packet length */
	old_mtu = netdev->mtu;
	netdev->mtu = mtu;
	if ( mtu != old_mtu ) {
	DBGC ( netdev, "NETDEV %s MTU is %zd\n",
	netdev->name, mtu );
	}

	/* Close and reopen network device if MTU has increased */
	if ( netdev_is_open ( netdev ) && ( mtu > old_mtu ) ) {
	netdev_close ( netdev );
	if ( ( rc = netdev_open ( netdev ) ) != 0 ) {
	DBGC ( netdev, "NETDEV %s could not reopen: "
	"%s\n", netdev->name, strerror ( rc ) );
	return rc;
	}
	}
	}

	return 0;
	}

	/** Network device settings applicator */
	struct settings_applicator netdev_applicator __settings_applicator = {
	.apply = apply_netdev_settings,
	};