Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933028AbbFQXRO (ORCPT ); Wed, 17 Jun 2015 19:17:14 -0400 Received: from mga09.intel.com ([134.134.136.24]:2300 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933013AbbFQXRH (ORCPT ); Wed, 17 Jun 2015 19:17:07 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.13,636,1427785200"; d="scan'208";a="729557749" Subject: [PATCH v7 12/16] libnvdimm: namespace indices: read and validate From: Dan Williams To: linux-nvdimm@ml01.01.org Cc: axboe@kernel.dk, sfr@canb.auug.org.au, rafael@kernel.org, neilb@suse.de, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, mingo@kernel.org, linux-acpi@vger.kernel.org, jmoyer@redhat.com, linux-api@vger.kernel.org, akpm@linux-foundation.org, hch@lst.de Date: Wed, 17 Jun 2015 19:14:25 -0400 Message-ID: <20150617231425.11597.76306.stgit@dwillia2-desk3.amr.corp.intel.com> In-Reply-To: <20150617215027.11597.61414.stgit@dwillia2-desk3.amr.corp.intel.com> References: <20150617215027.11597.61414.stgit@dwillia2-desk3.amr.corp.intel.com> User-Agent: StGit/0.17.1-8-g92dd MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 20074 Lines: 691 This on media label format [1] consists of two index blocks followed by an array of labels. None of these structures are ever updated in place. A sequence number tracks the current active index and the next one to write, while labels are written to free slots. +------------+ | | | nsindex0 | | | +------------+ | | | nsindex1 | | | +------------+ | label0 | +------------+ | label1 | +------------+ | | ....nslot... | | +------------+ | labelN | +------------+ After reading valid labels, store the dpa ranges they claim into per-dimm resource trees. [1]: http://pmem.io/documents/NVDIMM_Namespace_Spec.pdf Cc: Neil Brown Acked-by: Christoph Hellwig Signed-off-by: Dan Williams --- drivers/nvdimm/Makefile | 1 drivers/nvdimm/dimm.c | 23 +++ drivers/nvdimm/dimm_devs.c | 30 ++++- drivers/nvdimm/label.c | 290 ++++++++++++++++++++++++++++++++++++++++++++ drivers/nvdimm/label.h | 128 +++++++++++++++++++ drivers/nvdimm/nd.h | 49 +++++++ include/uapi/linux/ndctl.h | 1 7 files changed, 520 insertions(+), 2 deletions(-) create mode 100644 drivers/nvdimm/label.c create mode 100644 drivers/nvdimm/label.h diff --git a/drivers/nvdimm/Makefile b/drivers/nvdimm/Makefile index 4d2a27f52faa..abce98f87f16 100644 --- a/drivers/nvdimm/Makefile +++ b/drivers/nvdimm/Makefile @@ -10,3 +10,4 @@ libnvdimm-y += dimm.o libnvdimm-y += region_devs.o libnvdimm-y += region.o libnvdimm-y += namespace_devs.o +libnvdimm-y += label.o diff --git a/drivers/nvdimm/dimm.c b/drivers/nvdimm/dimm.c index eb20fc2df32b..2df97c3c3b34 100644 --- a/drivers/nvdimm/dimm.c +++ b/drivers/nvdimm/dimm.c @@ -18,6 +18,7 @@ #include #include #include +#include "label.h" #include "nd.h" static void free_data(struct nvdimm_drvdata *ndd) @@ -42,6 +43,11 @@ static int nvdimm_probe(struct device *dev) return -ENOMEM; dev_set_drvdata(dev, ndd); + ndd->dpa.name = dev_name(dev); + ndd->ns_current = -1; + ndd->ns_next = -1; + ndd->dpa.start = 0; + ndd->dpa.end = -1; ndd->dev = dev; rc = nvdimm_init_nsarea(ndd); @@ -54,6 +60,17 @@ static int nvdimm_probe(struct device *dev) dev_dbg(dev, "config data size: %d\n", ndd->nsarea.config_size); + nvdimm_bus_lock(dev); + ndd->ns_current = nd_label_validate(ndd); + ndd->ns_next = nd_label_next_nsindex(ndd->ns_current); + nd_label_copy(ndd, to_next_namespace_index(ndd), + to_current_namespace_index(ndd)); + rc = nd_label_reserve_dpa(ndd); + nvdimm_bus_unlock(dev); + + if (rc) + goto err; + return 0; err: @@ -64,7 +81,13 @@ static int nvdimm_probe(struct device *dev) static int nvdimm_remove(struct device *dev) { struct nvdimm_drvdata *ndd = dev_get_drvdata(dev); + struct resource *res, *_r; + nvdimm_bus_lock(dev); + dev_set_drvdata(dev, NULL); + for_each_dpa_resource_safe(ndd, res, _r) + nvdimm_free_dpa(ndd, res); + nvdimm_bus_unlock(dev); free_data(ndd); return 0; diff --git a/drivers/nvdimm/dimm_devs.c b/drivers/nvdimm/dimm_devs.c index bdf8241b6525..d2ef02e4be6c 100644 --- a/drivers/nvdimm/dimm_devs.c +++ b/drivers/nvdimm/dimm_devs.c @@ -92,8 +92,12 @@ int nvdimm_init_config_data(struct nvdimm_drvdata *ndd) if (ndd->data) return 0; - if (ndd->nsarea.status || ndd->nsarea.max_xfer == 0) + if (ndd->nsarea.status || ndd->nsarea.max_xfer == 0 + || ndd->nsarea.config_size < ND_LABEL_MIN_SIZE) { + dev_dbg(ndd->dev, "failed to init config data area: (%d:%d)\n", + ndd->nsarea.max_xfer, ndd->nsarea.config_size); return -ENXIO; + } ndd->data = kmalloc(ndd->nsarea.config_size, GFP_KERNEL); if (!ndd->data) @@ -243,6 +247,30 @@ struct nvdimm *nvdimm_create(struct nvdimm_bus *nvdimm_bus, void *provider_data, } EXPORT_SYMBOL_GPL(nvdimm_create); +void nvdimm_free_dpa(struct nvdimm_drvdata *ndd, struct resource *res) +{ + WARN_ON_ONCE(!is_nvdimm_bus_locked(ndd->dev)); + kfree(res->name); + __release_region(&ndd->dpa, res->start, resource_size(res)); +} + +struct resource *nvdimm_allocate_dpa(struct nvdimm_drvdata *ndd, + struct nd_label_id *label_id, resource_size_t start, + resource_size_t n) +{ + char *name = kmemdup(label_id, sizeof(*label_id), GFP_KERNEL); + struct resource *res; + + if (!name) + return NULL; + + WARN_ON_ONCE(!is_nvdimm_bus_locked(ndd->dev)); + res = __request_region(&ndd->dpa, start, n, name, 0); + if (!res) + kfree(name); + return res; +} + static int count_dimms(struct device *dev, void *c) { int *count = c; diff --git a/drivers/nvdimm/label.c b/drivers/nvdimm/label.c new file mode 100644 index 000000000000..db5d7492dc8d --- /dev/null +++ b/drivers/nvdimm/label.c @@ -0,0 +1,290 @@ +/* + * Copyright(c) 2013-2015 Intel Corporation. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of version 2 of the GNU General Public License as + * published by the Free Software Foundation. + * + * 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. + */ +#include +#include +#include +#include +#include "nd-core.h" +#include "label.h" +#include "nd.h" + +static u32 best_seq(u32 a, u32 b) +{ + a &= NSINDEX_SEQ_MASK; + b &= NSINDEX_SEQ_MASK; + + if (a == 0 || a == b) + return b; + else if (b == 0) + return a; + else if (nd_inc_seq(a) == b) + return b; + else + return a; +} + +size_t sizeof_namespace_index(struct nvdimm_drvdata *ndd) +{ + u32 index_span; + + if (ndd->nsindex_size) + return ndd->nsindex_size; + + /* + * The minimum index space is 512 bytes, with that amount of + * index we can describe ~1400 labels which is less than a byte + * of overhead per label. Round up to a byte of overhead per + * label and determine the size of the index region. Yes, this + * starts to waste space at larger config_sizes, but it's + * unlikely we'll ever see anything but 128K. + */ + index_span = ndd->nsarea.config_size / 129; + index_span /= NSINDEX_ALIGN * 2; + ndd->nsindex_size = index_span * NSINDEX_ALIGN; + + return ndd->nsindex_size; +} + +int nd_label_validate(struct nvdimm_drvdata *ndd) +{ + /* + * On media label format consists of two index blocks followed + * by an array of labels. None of these structures are ever + * updated in place. A sequence number tracks the current + * active index and the next one to write, while labels are + * written to free slots. + * + * +------------+ + * | | + * | nsindex0 | + * | | + * +------------+ + * | | + * | nsindex1 | + * | | + * +------------+ + * | label0 | + * +------------+ + * | label1 | + * +------------+ + * | | + * ....nslot... + * | | + * +------------+ + * | labelN | + * +------------+ + */ + struct nd_namespace_index *nsindex[] = { + to_namespace_index(ndd, 0), + to_namespace_index(ndd, 1), + }; + const int num_index = ARRAY_SIZE(nsindex); + struct device *dev = ndd->dev; + bool valid[2] = { 0 }; + int i, num_valid = 0; + u32 seq; + + for (i = 0; i < num_index; i++) { + u32 nslot; + u8 sig[NSINDEX_SIG_LEN]; + u64 sum_save, sum, size; + + memcpy(sig, nsindex[i]->sig, NSINDEX_SIG_LEN); + if (memcmp(sig, NSINDEX_SIGNATURE, NSINDEX_SIG_LEN) != 0) { + dev_dbg(dev, "%s: nsindex%d signature invalid\n", + __func__, i); + continue; + } + sum_save = __le64_to_cpu(nsindex[i]->checksum); + nsindex[i]->checksum = __cpu_to_le64(0); + sum = nd_fletcher64(nsindex[i], sizeof_namespace_index(ndd), 1); + nsindex[i]->checksum = __cpu_to_le64(sum_save); + if (sum != sum_save) { + dev_dbg(dev, "%s: nsindex%d checksum invalid\n", + __func__, i); + continue; + } + + seq = __le32_to_cpu(nsindex[i]->seq); + if ((seq & NSINDEX_SEQ_MASK) == 0) { + dev_dbg(dev, "%s: nsindex%d sequence: %#x invalid\n", + __func__, i, seq); + continue; + } + + /* sanity check the index against expected values */ + if (__le64_to_cpu(nsindex[i]->myoff) + != i * sizeof_namespace_index(ndd)) { + dev_dbg(dev, "%s: nsindex%d myoff: %#llx invalid\n", + __func__, i, (unsigned long long) + __le64_to_cpu(nsindex[i]->myoff)); + continue; + } + if (__le64_to_cpu(nsindex[i]->otheroff) + != (!i) * sizeof_namespace_index(ndd)) { + dev_dbg(dev, "%s: nsindex%d otheroff: %#llx invalid\n", + __func__, i, (unsigned long long) + __le64_to_cpu(nsindex[i]->otheroff)); + continue; + } + + size = __le64_to_cpu(nsindex[i]->mysize); + if (size > sizeof_namespace_index(ndd) + || size < sizeof(struct nd_namespace_index)) { + dev_dbg(dev, "%s: nsindex%d mysize: %#llx invalid\n", + __func__, i, size); + continue; + } + + nslot = __le32_to_cpu(nsindex[i]->nslot); + if (nslot * sizeof(struct nd_namespace_label) + + 2 * sizeof_namespace_index(ndd) + > ndd->nsarea.config_size) { + dev_dbg(dev, "%s: nsindex%d nslot: %u invalid, config_size: %#x\n", + __func__, i, nslot, + ndd->nsarea.config_size); + continue; + } + valid[i] = true; + num_valid++; + } + + switch (num_valid) { + case 0: + break; + case 1: + for (i = 0; i < num_index; i++) + if (valid[i]) + return i; + /* can't have num_valid > 0 but valid[] = { false, false } */ + WARN_ON(1); + break; + default: + /* pick the best index... */ + seq = best_seq(__le32_to_cpu(nsindex[0]->seq), + __le32_to_cpu(nsindex[1]->seq)); + if (seq == (__le32_to_cpu(nsindex[1]->seq) & NSINDEX_SEQ_MASK)) + return 1; + else + return 0; + break; + } + + return -1; +} + +void nd_label_copy(struct nvdimm_drvdata *ndd, struct nd_namespace_index *dst, + struct nd_namespace_index *src) +{ + if (dst && src) + /* pass */; + else + return; + + memcpy(dst, src, sizeof_namespace_index(ndd)); +} + +static struct nd_namespace_label *nd_label_base(struct nvdimm_drvdata *ndd) +{ + void *base = to_namespace_index(ndd, 0); + + return base + 2 * sizeof_namespace_index(ndd); +} + +#define for_each_clear_bit_le(bit, addr, size) \ + for ((bit) = find_next_zero_bit_le((addr), (size), 0); \ + (bit) < (size); \ + (bit) = find_next_zero_bit_le((addr), (size), (bit) + 1)) + +/** + * preamble_current - common variable initialization for nd_label_* routines + * @ndd: dimm container for the relevant label set + * @nsindex_out: on return set to the currently active namespace index + * @free: on return set to the free label bitmap in the index + * @nslot: on return set to the number of slots in the label space + */ +static bool preamble_current(struct nvdimm_drvdata *ndd, + struct nd_namespace_index **nsindex_out, + unsigned long **free, u32 *nslot) +{ + struct nd_namespace_index *nsindex; + + nsindex = to_current_namespace_index(ndd); + if (nsindex == NULL) + return false; + + *free = (unsigned long *) nsindex->free; + *nslot = __le32_to_cpu(nsindex->nslot); + *nsindex_out = nsindex; + + return true; +} + +static char *nd_label_gen_id(struct nd_label_id *label_id, u8 *uuid, u32 flags) +{ + if (!label_id || !uuid) + return NULL; + snprintf(label_id->id, ND_LABEL_ID_SIZE, "%s-%pUb", + flags & NSLABEL_FLAG_LOCAL ? "blk" : "pmem", uuid); + return label_id->id; +} + +static bool slot_valid(struct nd_namespace_label *nd_label, u32 slot) +{ + /* check that we are written where we expect to be written */ + if (slot != __le32_to_cpu(nd_label->slot)) + return false; + + /* check that DPA allocations are page aligned */ + if ((__le64_to_cpu(nd_label->dpa) + | __le64_to_cpu(nd_label->rawsize)) % SZ_4K) + return false; + + return true; +} + +int nd_label_reserve_dpa(struct nvdimm_drvdata *ndd) +{ + struct nd_namespace_index *nsindex; + unsigned long *free; + u32 nslot, slot; + + if (!preamble_current(ndd, &nsindex, &free, &nslot)) + return 0; /* no label, nothing to reserve */ + + for_each_clear_bit_le(slot, free, nslot) { + struct nd_namespace_label *nd_label; + struct nd_region *nd_region = NULL; + u8 label_uuid[NSLABEL_UUID_LEN]; + struct nd_label_id label_id; + struct resource *res; + u32 flags; + + nd_label = nd_label_base(ndd) + slot; + + if (!slot_valid(nd_label, slot)) + continue; + + memcpy(label_uuid, nd_label->uuid, NSLABEL_UUID_LEN); + flags = __le32_to_cpu(nd_label->flags); + nd_label_gen_id(&label_id, label_uuid, flags); + res = nvdimm_allocate_dpa(ndd, &label_id, + __le64_to_cpu(nd_label->dpa), + __le64_to_cpu(nd_label->rawsize)); + nd_dbg_dpa(nd_region, ndd, res, "reserve\n"); + if (!res) + return -EBUSY; + } + + return 0; +} diff --git a/drivers/nvdimm/label.h b/drivers/nvdimm/label.h new file mode 100644 index 000000000000..d6aa0d5c6b4e --- /dev/null +++ b/drivers/nvdimm/label.h @@ -0,0 +1,128 @@ +/* + * Copyright(c) 2013-2015 Intel Corporation. All rights reserved. + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of version 2 of the GNU General Public License as + * published by the Free Software Foundation. + * + * 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. + */ +#ifndef __LABEL_H__ +#define __LABEL_H__ + +#include +#include +#include + +enum { + NSINDEX_SIG_LEN = 16, + NSINDEX_ALIGN = 256, + NSINDEX_SEQ_MASK = 0x3, + NSLABEL_UUID_LEN = 16, + NSLABEL_NAME_LEN = 64, + NSLABEL_FLAG_ROLABEL = 0x1, /* read-only label */ + NSLABEL_FLAG_LOCAL = 0x2, /* DIMM-local namespace */ + NSLABEL_FLAG_BTT = 0x4, /* namespace contains a BTT */ + NSLABEL_FLAG_UPDATING = 0x8, /* label being updated */ + BTT_ALIGN = 4096, /* all btt structures */ + BTTINFO_SIG_LEN = 16, + BTTINFO_UUID_LEN = 16, + BTTINFO_FLAG_ERROR = 0x1, /* error state (read-only) */ + BTTINFO_MAJOR_VERSION = 1, + ND_LABEL_MIN_SIZE = 512 * 129, /* see sizeof_namespace_index() */ + ND_LABEL_ID_SIZE = 50, +}; + +static const char NSINDEX_SIGNATURE[] = "NAMESPACE_INDEX\0"; + +/** + * struct nd_namespace_index - label set superblock + * @sig: NAMESPACE_INDEX\0 + * @flags: placeholder + * @seq: sequence number for this index + * @myoff: offset of this index in label area + * @mysize: size of this index struct + * @otheroff: offset of other index + * @labeloff: offset of first label slot + * @nslot: total number of label slots + * @major: label area major version + * @minor: label area minor version + * @checksum: fletcher64 of all fields + * @free[0]: bitmap, nlabel bits + * + * The size of free[] is rounded up so the total struct size is a + * multiple of NSINDEX_ALIGN bytes. Any bits this allocates beyond + * nlabel bits must be zero. + */ +struct nd_namespace_index { + u8 sig[NSINDEX_SIG_LEN]; + __le32 flags; + __le32 seq; + __le64 myoff; + __le64 mysize; + __le64 otheroff; + __le64 labeloff; + __le32 nslot; + __le16 major; + __le16 minor; + __le64 checksum; + u8 free[0]; +}; + +/** + * struct nd_namespace_label - namespace superblock + * @uuid: UUID per RFC 4122 + * @name: optional name (NULL-terminated) + * @flags: see NSLABEL_FLAG_* + * @nlabel: num labels to describe this ns + * @position: labels position in set + * @isetcookie: interleave set cookie + * @lbasize: LBA size in bytes or 0 for pmem + * @dpa: DPA of NVM range on this DIMM + * @rawsize: size of namespace + * @slot: slot of this label in label area + * @unused: must be zero + */ +struct nd_namespace_label { + u8 uuid[NSLABEL_UUID_LEN]; + u8 name[NSLABEL_NAME_LEN]; + __le32 flags; + __le16 nlabel; + __le16 position; + __le64 isetcookie; + __le64 lbasize; + __le64 dpa; + __le64 rawsize; + __le32 slot; + __le32 unused; +}; + +/** + * struct nd_label_id - identifier string for dpa allocation + * @id: "{blk|pmem}-" + */ +struct nd_label_id { + char id[ND_LABEL_ID_SIZE]; +}; + +/* + * If the 'best' index is invalid, so is the 'next' index. Otherwise, + * the next index is MOD(index+1, 2) + */ +static inline int nd_label_next_nsindex(int index) +{ + if (index < 0) + return -1; + + return (index + 1) % 2; +} + +struct nvdimm_drvdata; +int nd_label_validate(struct nvdimm_drvdata *ndd); +void nd_label_copy(struct nvdimm_drvdata *ndd, struct nd_namespace_index *dst, + struct nd_namespace_index *src); +size_t sizeof_namespace_index(struct nvdimm_drvdata *ndd); +#endif /* __LABEL_H__ */ diff --git a/drivers/nvdimm/nd.h b/drivers/nvdimm/nd.h index 0285e4588b03..401fa0d5b6ea 100644 --- a/drivers/nvdimm/nd.h +++ b/drivers/nvdimm/nd.h @@ -16,11 +16,15 @@ #include #include #include +#include "label.h" struct nvdimm_drvdata { struct device *dev; + int nsindex_size; struct nd_cmd_get_config_size nsarea; void *data; + int ns_current, ns_next; + struct resource dpa; }; struct nd_region_namespaces { @@ -28,6 +32,37 @@ struct nd_region_namespaces { int active; }; +static inline struct nd_namespace_index *to_namespace_index( + struct nvdimm_drvdata *ndd, int i) +{ + if (i < 0) + return NULL; + + return ndd->data + sizeof_namespace_index(ndd) * i; +} + +static inline struct nd_namespace_index *to_current_namespace_index( + struct nvdimm_drvdata *ndd) +{ + return to_namespace_index(ndd, ndd->ns_current); +} + +static inline struct nd_namespace_index *to_next_namespace_index( + struct nvdimm_drvdata *ndd) +{ + return to_namespace_index(ndd, ndd->ns_next); +} + +#define nd_dbg_dpa(r, d, res, fmt, arg...) \ + dev_dbg((r) ? &(r)->dev : (d)->dev, "%s: %.13s: %#llx @ %#llx " fmt, \ + (r) ? dev_name((d)->dev) : "", res ? res->name : "null", \ + (unsigned long long) (res ? resource_size(res) : 0), \ + (unsigned long long) (res ? res->start : 0), ##arg) + +#define for_each_dpa_resource_safe(ndd, res, next) \ + for (res = (ndd)->dpa.child, next = res ? res->sibling : NULL; \ + res; res = next, next = next ? next->sibling : NULL) + struct nd_region { struct device dev; u16 ndr_mappings; @@ -39,6 +74,15 @@ struct nd_region { struct nd_mapping mapping[0]; }; +/* + * Lookup next in the repeating sequence of 01, 10, and 11. + */ +static inline unsigned nd_inc_seq(unsigned seq) +{ + static const unsigned next[] = { 0, 2, 3, 1 }; + + return next[seq & 3]; +} enum nd_async_mode { ND_SYNC, ND_ASYNC, @@ -58,4 +102,9 @@ int nd_region_register_namespaces(struct nd_region *nd_region, int *err); void nvdimm_bus_lock(struct device *dev); void nvdimm_bus_unlock(struct device *dev); bool is_nvdimm_bus_locked(struct device *dev); +int nd_label_reserve_dpa(struct nvdimm_drvdata *ndd); +void nvdimm_free_dpa(struct nvdimm_drvdata *ndd, struct resource *res); +struct resource *nvdimm_allocate_dpa(struct nvdimm_drvdata *ndd, + struct nd_label_id *label_id, resource_size_t start, + resource_size_t n); #endif /* __ND_H__ */ diff --git a/include/uapi/linux/ndctl.h b/include/uapi/linux/ndctl.h index 174b6371dcc1..1357a87b8714 100644 --- a/include/uapi/linux/ndctl.h +++ b/include/uapi/linux/ndctl.h @@ -175,7 +175,6 @@ static inline const char *nvdimm_cmd_name(unsigned cmd) #define ND_IOCTL_ARS_STATUS _IOWR(ND_IOCTL, ND_CMD_ARS_STATUS,\ struct nd_cmd_ars_status) - #define ND_DEVICE_DIMM 1 /* nd_dimm: container for "config data" */ #define ND_DEVICE_REGION_PMEM 2 /* nd_region: (parent of PMEM namespaces) */ #define ND_DEVICE_REGION_BLK 3 /* nd_region: (parent of BLK namespaces) */ -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/