On Wed, 2009-12-09 at 09:58 +0800, Zhao, Yakui wrote:
Hi, Lenb
Any comment about this patch?
It is used to add the support of ACPI IPMI opregion so that ACPI can
also communicate with the BMC controller.
Thanks.
Yakui
> From: Zhao Yakui <yakui.zhao@xxxxxxxxx>
>
> Add the IPMI opregion driver so that the AML code can communicate with BMC
> throught IPMI message.
> It will create IPMI user interface for every IPMI device detected
> in ACPI namespace and install the corresponding IPMI opregion space handler.
>
> The following describes how to process the IPMI request in IPMI space handler:
> 1. format the IPMI message based on the request in AML code.
> IPMI system address. Now the address type is SYSTEM_INTERFACE_ADDR_TYPE
> IPMI net function & command
> IPMI message payload
> 2. send the IPMI message by using the function of ipmi_request_settime
> 3. wait for the completion of IPMI message. It can be done in different
> routes: One is in handled in IPMI user recv callback function. Another is
> handled in timeout function.
> 4. format the IPMI response and return it to ACPI AML code.
>
> Signed-off-by: Zhao Yakui <yakui.zhao@xxxxxxxxx>
> ---
> drivers/acpi/Kconfig | 12 +
> drivers/acpi/Makefile | 1 +
> drivers/acpi/ipmi.c | 583 +++++++++++++++++++++++++++++++++++++++++++++++++
> 3 files changed, 596 insertions(+), 0 deletions(-)
> create mode 100644 drivers/acpi/ipmi.c
>
> diff --git a/drivers/acpi/Kconfig b/drivers/acpi/Kconfig
> index 93d2c79..23cd08a 100644
> --- a/drivers/acpi/Kconfig
> +++ b/drivers/acpi/Kconfig
> @@ -204,6 +204,18 @@ config ACPI_PROCESSOR
>
> To compile this driver as a module, choose M here:
> the module will be called processor.
> +config ACPI_IPMI
> + tristate "IPMI"
> + depends on EXPERIMENTAL
> + default n
> + select IPMI_HANDLER
> + select IPMI_SI
> + help
> + This driver enables the ACPI to access the BMC controller. And it
> + uses the IPMI request/response message to communicate with BMC
> + controller, which can be found on on the server.
> +
> + To compile this driver as a module, choose M here:
>
> config ACPI_HOTPLUG_CPU
> bool
> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> index 7702118..61077b7 100644
> --- a/drivers/acpi/Makefile
> +++ b/drivers/acpi/Makefile
> @@ -57,6 +57,7 @@ obj-$(CONFIG_ACPI_BATTERY) += battery.o
> obj-$(CONFIG_ACPI_SBS) += sbshc.o
> obj-$(CONFIG_ACPI_SBS) += sbs.o
> obj-$(CONFIG_ACPI_POWER_METER) += power_meter.o
> +obj-$(CONFIG_ACPI_IPMI) += ipmi.o
>
> # processor has its own "processor." module_param namespace
> processor-y := processor_core.o processor_throttling.o
> diff --git a/drivers/acpi/ipmi.c b/drivers/acpi/ipmi.c
> new file mode 100644
> index 0000000..5c74936
> --- /dev/null
> +++ b/drivers/acpi/ipmi.c
> @@ -0,0 +1,583 @@
> +/*
> + * ipmi.c - ACPI IPMI opregion
> + *
> + * Copyright (C) 2009 Intel Corporation
> + * Copyright (C) 2009 Zhao Yakui <yakui.zhao@xxxxxxxxx>
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + *
> + * 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 (at
> + * your option) 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.,
> + * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
> + *
> + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/init.h>
> +#include <linux/types.h>
> +#include <linux/delay.h>
> +#include <linux/proc_fs.h>
> +#include <linux/seq_file.h>
> +#include <linux/interrupt.h>
> +#include <linux/list.h>
> +#include <linux/spinlock.h>
> +#include <linux/io.h>
> +#include <acpi/acpi_bus.h>
> +#include <acpi/acpi_drivers.h>
> +#include <linux/ipmi.h>
> +
> +MODULE_AUTHOR("Zhao Yakui");
> +MODULE_DESCRIPTION("ACPI IPMI Opregion driver");
> +MODULE_LICENSE("GPL");
> +
> +#define ACPI_IPMI_CLASS "IPMI"
> +#define ACPI_IPMI_DEVICE_NAME "IPMI_dev"
> +#define IPMI_FLAGS_HANDLER_INSTALL 0
> +
> +#define ACPI_IPMI_OK 0
> +#define ACPI_IPMI_TIMEOUT 0x10
> +#define ACPI_IPMI_UNKNOWN 0x07
> +/* the IPMI timeout is 30s */
> +#define IPMI_TIMEOUT (30 * HZ)
> +
> +
> +struct acpi_ipmi_device {
> + acpi_handle handle;
> + struct acpi_device *device;
> + int if_type;
> + /* the device list attached to driver_data.ipmi_devices */
> + struct list_head head;
> + ipmi_user_t user_interface;
> + struct mutex mutex_lock;
> + /* the IPMI request message list */
> + struct list_head tx_msg_list;
> + long curr_msgid;
> + /* IPMI flags */
> + unsigned long flags;
> +};
> +
> +struct ipmi_driver_data {
> + int device_count;
> + struct list_head ipmi_devices;
> + struct ipmi_smi_watcher bmc_events;
> + struct ipmi_user_hndl ipmi_hndlrs;
> +};
> +
> +struct acpi_ipmi_msg {
> + /* message list */
> + struct list_head head;
> + /*
> + * General speaking the addr type should be SI_ADDR_TYPE. And
> + * the addr channel should be BMC.
> + * In fact it can also be IPMB type. But we will have to
> + * parse it from the Netfn command buffer. It is so complex
> + * that it is skipped.
> + */
> + struct ipmi_addr addr;
> + /* tx message id */
> + long tx_msgid;
> + /* it is used to track whether the IPMI message is finished */
> + struct completion tx_complete;
> + struct kernel_ipmi_msg tx_message;
> + int msg_done;
> + /* tx data . And copy it from ACPI object buffer */
> + u8 tx_data[64];
> + int tx_len;
> + /* get the response data */
> + u8 rx_data[64];
> + /* the response length. The netfn & cmd is excluded. */
> + int rx_len;
> + struct acpi_ipmi_device *device;
> +};
> +
> +/*
> + * IPMI request/response buffer.
> + * The length is 66 bytes.
> + */
> +struct acpi_ipmi_buffer {
> + /* status code of a given IPMI command */
> + u8 status_code;
> + /* the length of the payload */
> + u8 length;
> + /*
> + * the payload. Before the operation is carried out, it represents the
> + * request message payload. After the opration is carried out, it
> + * stores the response message returned by IPMI command.
> + */
> + u8 data[64];
> +};
> +
> +static void ipmi_register_bmc(int iface, struct device *dev);
> +static void ipmi_bmc_gone(int iface);
> +static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data);
> +
> +static struct ipmi_driver_data driver_data = {
> + .ipmi_devices = LIST_HEAD_INIT(driver_data.ipmi_devices),
> + .bmc_events = {
> + .owner = THIS_MODULE,
> + .new_smi = ipmi_register_bmc,
> + .smi_gone = ipmi_bmc_gone,
> + },
> + .ipmi_hndlrs = {
> + .ipmi_recv_hndl = ipmi_msg_handler,
> + },
> +};
> +
> +static
> +struct acpi_ipmi_msg *acpi_alloc_ipmi_msg(struct acpi_ipmi_device *ipmi)
> +{
> + struct acpi_ipmi_msg *ipmi_msg;
> +
> + ipmi_msg = kzalloc(sizeof(struct acpi_ipmi_msg), GFP_KERNEL);
> + if (!ipmi_msg) {
> + printk(KERN_DEBUG "Can't allocate memory for ipmi_msg\n");
> + return NULL;
> + }
> + init_completion(&ipmi_msg->tx_complete);
> + INIT_LIST_HEAD(&ipmi_msg->head);
> + ipmi_msg->device = ipmi;
> + return ipmi_msg;
> +}
> +
> +static void acpi_format_ipmi_msg(struct acpi_ipmi_msg *tx_msg,
> + acpi_physical_address address,
> + acpi_integer *value)
> +{
> + struct kernel_ipmi_msg *msg;
> + u8 temp_value;
> + struct acpi_ipmi_buffer *buffer;
> + struct acpi_ipmi_device *device;
> +
> + msg = &tx_msg->tx_message;
> + /* get the netfn */
> + temp_value = (address >> 8) & 0xff;
> + msg->netfn = temp_value;
> + /* get the command */
> + temp_value = address & 0xff;
> + msg->cmd = temp_value;
> + msg->data = tx_msg->tx_data;
> + /*
> + * value is the parameter passed by the IPMI opregion space handler.
> + * It points to the IPMI request message buffer
> + */
> + buffer = (struct acpi_ipmi_buffer *)value;
> + /* copy the tx message data */
> + msg->data_len = buffer->length;
> + memcpy(tx_msg->tx_data, buffer->data, msg->data_len);
> + /*
> + * now the default type is SYSTEM_INTERFACE and channel type is BMC.
> + * If the netfn is APP_REQUEST and the cmd is SEND_MESSAGE,
> + * the addr type should be changed to IPMB.
> + */
> + tx_msg->addr.addr_type = IPMI_SYSTEM_INTERFACE_ADDR_TYPE;
> + tx_msg->addr.channel = IPMI_BMC_CHANNEL;
> + tx_msg->addr.data[0] = 0;
> +
> + /*
> + * If the netfn is APP_REQUEST and the cmd is SEND_MESSAGE, we should
> + * parse the IPMI request message buffer to get the IPMB address.
> + * If so, please fix me.
> + */
> +
> + /* Get the msgid */
> + device = tx_msg->device;
> + mutex_lock(&device->mutex_lock);
> + device->curr_msgid++;
> + tx_msg->tx_msgid = device->curr_msgid;
> + mutex_unlock(&device->mutex_lock);
> +}
> +
> +static void acpi_format_ipmi_response(struct acpi_ipmi_msg *msg,
> + acpi_integer *value, int timeout)
> +{
> + struct acpi_ipmi_buffer *buffer;
> +
> + /*
> + * value is also used as output parameter. It represents the response
> + * IPMI message returned by IPMI command.
> + */
> + buffer = (struct acpi_ipmi_buffer *)value;
> + /* when timeout is zero, it means that the timeout happens */
> + if (!timeout) {
> + /* the status code is ACPI_IPMI_TIMEOUT */
> + buffer->status_code = ACPI_IPMI_TIMEOUT;
> + return;
> + }
> + /*
> + * If the flag of msg_done is not set, it means that the IPMI command
> + * is not executed correctly.
> + * The status code will be ACPI_IPMI_UNKNOWN.
> + */
> + if (!msg->msg_done) {
> + buffer->status_code = ACPI_IPMI_UNKNOWN;
> + return;
> + }
> + /*
> + * If the IPMI response message is obtained correctly, the status code
> + * will be ACPI_IPMI_OK
> + */
> + buffer->status_code = ACPI_IPMI_OK;
> + buffer->length = msg->rx_len;
> + memcpy(buffer->data, msg->rx_data, msg->rx_len);
> + return;
> +}
> +static void ipmi_destroy_tx_msg(struct acpi_ipmi_device *ipmi)
> +{
> + struct acpi_ipmi_msg *tx_msg = NULL;
> + int count = 20;
> +
> + list_for_each_entry(tx_msg, &ipmi->tx_msg_list, head) {
> + /* wake up the sleep thread on the Tx msg */
> + complete(&tx_msg->tx_complete);
> + }
> + /* wait for about 20 ticks to flush the tx message list */
> + while (count--) {
> + if (list_empty(&ipmi->tx_msg_list))
> + break;
> + schedule_timeout(1);
> + }
> + if (!list_empty(&ipmi->tx_msg_list))
> + printk(KERN_DEBUG "tx msg list is not NULL\n");
> +
> +}
> +
> +static void ipmi_msg_handler(struct ipmi_recv_msg *msg, void *user_msg_data)
> +{
> + struct acpi_ipmi_device *ipmi_device =
> + (struct acpi_ipmi_device *)user_msg_data;
> + int msg_found = 0;
> + struct acpi_ipmi_msg *tx_msg = NULL;
> +
> + if (msg->user != ipmi_device->user_interface) {
> + printk(KERN_DEBUG "Incorrect IPMI user\n");
> + ipmi_free_recv_msg(msg);
> + return;
> + }
> + mutex_lock(&ipmi_device->mutex_lock);
> + list_for_each_entry(tx_msg, &ipmi_device->tx_msg_list, head) {
> + if (msg->msgid == tx_msg->tx_msgid) {
> + /* find the message id */
> + msg_found = 1;
> + break;
> + }
> + }
> +
> + mutex_unlock(&ipmi_device->mutex_lock);
> + if (!msg_found) {
> + /* no matched msg is found . But we should free it */
> + ipmi_free_recv_msg(msg);
> + printk(KERN_DEBUG "Incorrect MSG is found \n");
> + return;
> + }
> +
> + if (msg->msg.data_len > 1) {
> + /* copy the response data to Rx_data buffer */
> + memcpy(tx_msg->rx_data, msg->msg_data, msg->msg.data_len);
> + tx_msg->rx_len = msg->msg.data_len;
> + tx_msg->msg_done = 1;
> + }
> + complete(&tx_msg->tx_complete);
> + ipmi_free_recv_msg(msg);
> +};
> +
> +static void ipmi_register_bmc(int iface, struct device *dev)
> +{
> + struct acpi_ipmi_device *ipmi_device;
> + struct acpi_device *device;
> + ipmi_user_t user;
> + int err;
> +
> + if (list_empty(&driver_data.ipmi_devices))
> + return;
> +
> + list_for_each_entry(ipmi_device, &driver_data.ipmi_devices, head) {
> + device = ipmi_device->device;
> + if (ipmi_device->user_interface) {
> + /*
> + * Only one user interface is allowed to be registered
> + * for one IPMI device.
> + * If we already create the user interface for
> + * one IPMI device, skip it
> + */
> + continue;
> + }
> + if (dev == &device->dev) {
> + /*
> + * If the dev is identical to the ACPI device,
> + * create the user interface.
> + */
> + err = ipmi_create_user(iface, &driver_data.ipmi_hndlrs,
> + ipmi_device, &user);
> + if (err == 0)
> + ipmi_device->user_interface = user;
> +
> + continue;
> + }
> + /*
> + * In fact maybe the IPMI interface can be registered by
> + * other methods. For example: SPMI, DMI, PCI
> + * So we should also create the user interface.
> + */
> + err = ipmi_create_user(iface, &driver_data.ipmi_hndlrs,
> + ipmi_device, &user);
> + if (err == 0)
> + ipmi_device->user_interface = user;
> + }
> + return;
> +}
> +
> +static void ipmi_bmc_gone(int iface)
> +{
> + struct acpi_ipmi_device *ipmi_device;
> +
> + if (list_empty(&driver_data.ipmi_devices))
> + return;
> +
> + list_for_each_entry(ipmi_device, &driver_data.ipmi_devices, head) {
> + if (ipmi_device->user_interface) {
> + ipmi_destroy_user(ipmi_device->user_interface);
> + ipmi_device->user_interface = NULL;
> + /* we should also destory tx msg list */
> + ipmi_destroy_tx_msg(ipmi_device);
> + }
> + }
> +}
> +/* --------------------------------------------------------------------------
> + * Address Space Management
> + -------------------------------------------------------------------------- */
> +/*
> + * This is the IPMI opregion space handler.
> + * @function: indicates the read/write. In fact as the IPMI message is driven
> + * by command, only write is meaningful.
> + * @address: This contains the netfn/command of IPMI request message.
> + * @bits : not used.
> + * @value : it is an in/out parameter. It points to the IPMI message buffer.
> + * Before the IPMI message is sent, it represents the actual request
> + * IPMI message. After the IPMI message is finished, it represents
> + * the response IPMI message returned by IPMI command.
> + * @handler_context: IPMI device context.
> + */
> +
> +static acpi_status
> +acpi_ipmi_space_handler(u32 function, acpi_physical_address address,
> + u32 bits, acpi_integer *value,
> + void *handler_context, void *region_context)
> +{
> + struct acpi_ipmi_msg *tx_msg = NULL;
> + struct acpi_ipmi_device *ipmi_device =
> + (struct acpi_ipmi_device *) handler_context;
> + int err;
> + acpi_status status;
> + /*
> + * IPMI opregion message.
> + * IPMI message is firstly written to the BMC and system software
> + * can get the respsonse. So it is unmeaningful for the IPMI read
> + * access.
> + */
> + if ((function & ACPI_IO_MASK) == ACPI_READ) {
> + /* Read function is not supported. AE_TYPE is returned. */
> + return AE_TYPE;
> + }
> + if (!ipmi_device->user_interface) {
> + /* there doesn't exist user interface*/
> + return AE_NOT_EXIST;
> + }
> + tx_msg = acpi_alloc_ipmi_msg(ipmi_device);
> + if (!tx_msg) {
> + /* no memory is allocated */
> + return AE_NO_MEMORY;
> + }
> + acpi_format_ipmi_msg(tx_msg, address, value);
> + mutex_lock(&ipmi_device->mutex_lock);
> + list_add_tail(&tx_msg->head, &ipmi_device->tx_msg_list);
> + mutex_unlock(&ipmi_device->mutex_lock);
> + err = ipmi_request_settime(ipmi_device->user_interface,
> + &tx_msg->addr,
> + tx_msg->tx_msgid,
> + &tx_msg->tx_message,
> + NULL, 0, 0, 0);
> + if (err) {
> + status = AE_ERROR;
> + goto end_label;
> + }
> + err = wait_for_completion_timeout(&tx_msg->tx_complete, IPMI_TIMEOUT);
> +
> +end_label:
> + acpi_format_ipmi_response(tx_msg, value, err);
> + status = AE_OK;
> + mutex_lock(&ipmi_device->mutex_lock);
> + list_del(&tx_msg->head);
> + mutex_unlock(&ipmi_device->mutex_lock);
> + kfree(tx_msg);
> + return status;
> +}
> +
> +static void ipmi_remove_handlers(struct acpi_ipmi_device *ipmi)
> +{
> + if (!test_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags))
> + return;
> + acpi_remove_address_space_handler(ipmi->handle,
> + ACPI_ADR_SPACE_IPMI, &acpi_ipmi_space_handler);
> +
> + clear_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags);
> +}
> +
> +static int ipmi_install_handlers(struct acpi_ipmi_device *ipmi)
> +{
> + acpi_status status;
> +
> + if (test_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags))
> + return 0;
> +
> + status = acpi_install_address_space_handler(ipmi->handle,
> + ACPI_ADR_SPACE_IPMI,
> + &acpi_ipmi_space_handler,
> + NULL, ipmi);
> + if (ACPI_FAILURE(status)) {
> + printk(KERN_DEBUG "Can't register IPMI opregion %s\n",
> + acpi_device_bid(ipmi->device));
> + return -EINVAL;
> + }
> + set_bit(IPMI_FLAGS_HANDLER_INSTALL, &ipmi->flags);
> + return 0;
> +}
> +
> +static int acpi_ipmi_add(struct acpi_device *device)
> +{
> + struct acpi_ipmi_device *ipmi_device;
> + acpi_handle handle;
> + unsigned long long temp;
> + acpi_status status;
> + if (!device)
> + return -EINVAL;
> +
> + handle = device->handle;
> + temp = 0;
> + status = acpi_evaluate_integer(handle, "_IFT", NULL, &temp);
> + if (ACPI_FAILURE(status)) {
> + printk(KERN_DEBUG "Incorrect _IFT object for %s\n",
> + acpi_device_bid(device));
> + return -ENODEV;
> + }
> + ipmi_device = kzalloc(sizeof(struct acpi_ipmi_device), GFP_KERNEL);
> + if (!ipmi_device) {
> + printk(KERN_DEBUG "Can't allocate memory space\n");
> + return -ENOMEM;
> + }
> + ipmi_device->if_type = temp;
> + switch (ipmi_device->if_type) {
> + case 1:
> + case 2:
> + case 3:
> + break;
> + default:
> + printk(KERN_DEBUG "Unknow IPMI:SI interface type %d\n",
> + ipmi_device->if_type);
> + kfree(ipmi_device);
> + return -EINVAL;
> + }
> + ipmi_device->handle = device->handle;
> + ipmi_device->device = device;
> + mutex_init(&ipmi_device->mutex_lock);
> + INIT_LIST_HEAD(&ipmi_device->head);
> + INIT_LIST_HEAD(&ipmi_device->tx_msg_list);
> +
> + if (ipmi_install_handlers(ipmi_device)) {
> + /* can't register the IPMI opregion */
> + kfree(ipmi_device);
> + return -EINVAL;
> + }
> +
> + /* add it to the IPMI device list */
> + list_add_tail(&ipmi_device->head, &driver_data.ipmi_devices);
> + device->driver_data = ipmi_device;
> + return 0;
> +}
> +
> +static int acpi_ipmi_remove(struct acpi_device *device, int type)
> +{
> + struct acpi_ipmi_device *ipmi_device;
> +
> + ipmi_device = acpi_driver_data(device);
> + if (!ipmi_device)
> + return 0;
> +
> + if (ipmi_device->user_interface) {
> + /*
> + * If the IPMI user interface is created, it should be
> + * destroyed.
> + */
> + ipmi_destroy_user(ipmi_device->user_interface);
> + ipmi_device->user_interface = NULL;
> + }
> + list_del(&ipmi_device->head);
> + if (!list_empty(&ipmi_device->tx_msg_list)) {
> + /* destroy the Tx_msg list */
> + ipmi_destroy_tx_msg(ipmi_device);
> + }
> + ipmi_remove_handlers(ipmi_device);
> + kfree(ipmi_device);
> + device->driver_data = NULL;
> + return 0;
> +}
> +
> +static const struct acpi_device_id ipmi_device_ids[] = {
> + {"IPI0001", 0},
> + {"", 0},
> +};
> +
> +static struct acpi_driver acpi_ipmi_driver = {
> + .name = "ipmi",
> + .class = ACPI_IPMI_CLASS,
> + .ids = ipmi_device_ids,
> + .ops = {
> + .add = acpi_ipmi_add,
> + .remove = acpi_ipmi_remove,
> + },
> +};
> +
> +static int __init acpi_ipmi_init(void)
> +{
> + int result = 0;
> +
> + if (acpi_disabled)
> + return result;
> +
> + result = acpi_bus_register_driver(&acpi_ipmi_driver);
> +
> + if (result)
> + return result;
> +
> + result = ipmi_smi_watcher_register(&driver_data.bmc_events);
> +
> + if (result)
> + acpi_bus_unregister_driver(&acpi_ipmi_driver);
> +
> + return result;
> +}
> +
> +static void __exit acpi_ipmi_exit(void)
> +{
> + if (acpi_disabled)
> + return;
> +
> + ipmi_smi_watcher_unregister(&driver_data.bmc_events);
> + acpi_bus_unregister_driver(&acpi_ipmi_driver);
> +
> + return;
> +}
> +
> +module_init(acpi_ipmi_init);
> +module_exit(acpi_ipmi_exit);
> --
> 1.5.4.5
>
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
