@@ -74,10 +74,11 @@ config X86
select ARCH_HAS_ACPI_TABLE_UPGRADE if ACPI
select ARCH_HAS_CACHE_LINE_SIZE
select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION
select ARCH_HAS_CPU_FINALIZE_INIT
select ARCH_HAS_CPU_PASID if IOMMU_SVA
+ select ARCH_HAS_CRC32
select ARCH_HAS_CURRENT_STACK_POINTER
select ARCH_HAS_DEBUG_VIRTUAL
select ARCH_HAS_DEBUG_VM_PGTABLE if !X86_PAE
select ARCH_HAS_DEVMEM_IS_ALLOWED
select ARCH_HAS_DMA_OPS if GART_IOMMU || XEN
@@ -490,32 +490,10 @@ config CRYPTO_GHASH_CLMUL_NI_INTEL
GCM GHASH hash function (NIST SP800-38D)
Architecture: x86_64 using:
- CLMUL-NI (carry-less multiplication new instructions)
-config CRYPTO_CRC32C_INTEL
- tristate "CRC32c (SSE4.2/PCLMULQDQ)"
- depends on X86
- select CRYPTO_HASH
- help
- CRC32c CRC algorithm with the iSCSI polynomial (RFC 3385 and RFC 3720)
-
- Architecture: x86 (32-bit and 64-bit) using:
- - SSE4.2 (Streaming SIMD Extensions 4.2) CRC32 instruction
- - PCLMULQDQ (carry-less multiplication)
-
-config CRYPTO_CRC32_PCLMUL
- tristate "CRC32 (PCLMULQDQ)"
- depends on X86
- select CRYPTO_HASH
- select CRC32
- help
- CRC32 CRC algorithm (IEEE 802.3)
-
- Architecture: x86 (32-bit and 64-bit) using:
- - PCLMULQDQ (carry-less multiplication)
-
config CRYPTO_CRCT10DIF_PCLMUL
tristate "CRCT10DIF (PCLMULQDQ)"
depends on X86 && 64BIT && CRC_T10DIF
select CRYPTO_HASH
help
@@ -73,17 +73,10 @@ obj-$(CONFIG_CRYPTO_GHASH_CLMUL_NI_INTEL) += ghash-clmulni-intel.o
ghash-clmulni-intel-y := ghash-clmulni-intel_asm.o ghash-clmulni-intel_glue.o
obj-$(CONFIG_CRYPTO_POLYVAL_CLMUL_NI) += polyval-clmulni.o
polyval-clmulni-y := polyval-clmulni_asm.o polyval-clmulni_glue.o
-obj-$(CONFIG_CRYPTO_CRC32C_INTEL) += crc32c-intel.o
-crc32c-intel-y := crc32c-intel_glue.o
-crc32c-intel-$(CONFIG_64BIT) += crc32c-pcl-intel-asm_64.o
-
-obj-$(CONFIG_CRYPTO_CRC32_PCLMUL) += crc32-pclmul.o
-crc32-pclmul-y := crc32-pclmul_asm.o crc32-pclmul_glue.o
-
obj-$(CONFIG_CRYPTO_CRCT10DIF_PCLMUL) += crct10dif-pclmul.o
crct10dif-pclmul-y := crct10dif-pcl-asm_64.o crct10dif-pclmul_glue.o
obj-$(CONFIG_CRYPTO_POLY1305_X86_64) += poly1305-x86_64.o
poly1305-x86_64-y := poly1305-x86_64-cryptogams.o poly1305_glue.o
deleted file mode 100644
@@ -1,202 +0,0 @@
-/* GPL HEADER START
- *
- * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
- *
- * This program is free software; you can redistribute it and/or modify
- * it under the terms of the GNU General Public License version 2 only,
- * 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 version 2 for more details (a copy is included
- * in the LICENSE file that accompanied this code).
- *
- * You should have received a copy of the GNU General Public License
- * version 2 along with this program; If not, see http://www.gnu.org/licenses
- *
- * Please visit http://www.xyratex.com/contact if you need additional
- * information or have any questions.
- *
- * GPL HEADER END
- */
-
-/*
- * Copyright 2012 Xyratex Technology Limited
- *
- * Wrappers for kernel crypto shash api to pclmulqdq crc32 implementation.
- */
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/string.h>
-#include <linux/kernel.h>
-#include <linux/crc32.h>
-#include <crypto/internal/hash.h>
-#include <crypto/internal/simd.h>
-
-#include <asm/cpufeatures.h>
-#include <asm/cpu_device_id.h>
-#include <asm/simd.h>
-
-#define CHKSUM_BLOCK_SIZE 1
-#define CHKSUM_DIGEST_SIZE 4
-
-#define PCLMUL_MIN_LEN 64L /* minimum size of buffer
- * for crc32_pclmul_le_16 */
-#define SCALE_F 16L /* size of xmm register */
-#define SCALE_F_MASK (SCALE_F - 1)
-
-u32 crc32_pclmul_le_16(u32 crc, const u8 *buffer, size_t len);
-
-static u32 __attribute__((pure))
- crc32_pclmul_le(u32 crc, unsigned char const *p, size_t len)
-{
- unsigned int iquotient;
- unsigned int iremainder;
- unsigned int prealign;
-
- if (len < PCLMUL_MIN_LEN + SCALE_F_MASK || !crypto_simd_usable())
- return crc32_le(crc, p, len);
-
- if ((long)p & SCALE_F_MASK) {
- /* align p to 16 byte */
- prealign = SCALE_F - ((long)p & SCALE_F_MASK);
-
- crc = crc32_le(crc, p, prealign);
- len -= prealign;
- p = (unsigned char *)(((unsigned long)p + SCALE_F_MASK) &
- ~SCALE_F_MASK);
- }
- iquotient = len & (~SCALE_F_MASK);
- iremainder = len & SCALE_F_MASK;
-
- kernel_fpu_begin();
- crc = crc32_pclmul_le_16(crc, p, iquotient);
- kernel_fpu_end();
-
- if (iremainder)
- crc = crc32_le(crc, p + iquotient, iremainder);
-
- return crc;
-}
-
-static int crc32_pclmul_cra_init(struct crypto_tfm *tfm)
-{
- u32 *key = crypto_tfm_ctx(tfm);
-
- *key = 0;
-
- return 0;
-}
-
-static int crc32_pclmul_setkey(struct crypto_shash *hash, const u8 *key,
- unsigned int keylen)
-{
- u32 *mctx = crypto_shash_ctx(hash);
-
- if (keylen != sizeof(u32))
- return -EINVAL;
- *mctx = le32_to_cpup((__le32 *)key);
- return 0;
-}
-
-static int crc32_pclmul_init(struct shash_desc *desc)
-{
- u32 *mctx = crypto_shash_ctx(desc->tfm);
- u32 *crcp = shash_desc_ctx(desc);
-
- *crcp = *mctx;
-
- return 0;
-}
-
-static int crc32_pclmul_update(struct shash_desc *desc, const u8 *data,
- unsigned int len)
-{
- u32 *crcp = shash_desc_ctx(desc);
-
- *crcp = crc32_pclmul_le(*crcp, data, len);
- return 0;
-}
-
-/* No final XOR 0xFFFFFFFF, like crc32_le */
-static int __crc32_pclmul_finup(u32 *crcp, const u8 *data, unsigned int len,
- u8 *out)
-{
- *(__le32 *)out = cpu_to_le32(crc32_pclmul_le(*crcp, data, len));
- return 0;
-}
-
-static int crc32_pclmul_finup(struct shash_desc *desc, const u8 *data,
- unsigned int len, u8 *out)
-{
- return __crc32_pclmul_finup(shash_desc_ctx(desc), data, len, out);
-}
-
-static int crc32_pclmul_final(struct shash_desc *desc, u8 *out)
-{
- u32 *crcp = shash_desc_ctx(desc);
-
- *(__le32 *)out = cpu_to_le32p(crcp);
- return 0;
-}
-
-static int crc32_pclmul_digest(struct shash_desc *desc, const u8 *data,
- unsigned int len, u8 *out)
-{
- return __crc32_pclmul_finup(crypto_shash_ctx(desc->tfm), data, len,
- out);
-}
-
-static struct shash_alg alg = {
- .setkey = crc32_pclmul_setkey,
- .init = crc32_pclmul_init,
- .update = crc32_pclmul_update,
- .final = crc32_pclmul_final,
- .finup = crc32_pclmul_finup,
- .digest = crc32_pclmul_digest,
- .descsize = sizeof(u32),
- .digestsize = CHKSUM_DIGEST_SIZE,
- .base = {
- .cra_name = "crc32",
- .cra_driver_name = "crc32-pclmul",
- .cra_priority = 200,
- .cra_flags = CRYPTO_ALG_OPTIONAL_KEY,
- .cra_blocksize = CHKSUM_BLOCK_SIZE,
- .cra_ctxsize = sizeof(u32),
- .cra_module = THIS_MODULE,
- .cra_init = crc32_pclmul_cra_init,
- }
-};
-
-static const struct x86_cpu_id crc32pclmul_cpu_id[] = {
- X86_MATCH_FEATURE(X86_FEATURE_PCLMULQDQ, NULL),
- {}
-};
-MODULE_DEVICE_TABLE(x86cpu, crc32pclmul_cpu_id);
-
-
-static int __init crc32_pclmul_mod_init(void)
-{
-
- if (!x86_match_cpu(crc32pclmul_cpu_id)) {
- pr_info("PCLMULQDQ-NI instructions are not detected.\n");
- return -ENODEV;
- }
- return crypto_register_shash(&alg);
-}
-
-static void __exit crc32_pclmul_mod_fini(void)
-{
- crypto_unregister_shash(&alg);
-}
-
-module_init(crc32_pclmul_mod_init);
-module_exit(crc32_pclmul_mod_fini);
-
-MODULE_AUTHOR("Alexander Boyko <alexander_boyko@xyratex.com>");
-MODULE_DESCRIPTION("CRC32 algorithm (IEEE 802.3) accelerated with PCLMULQDQ");
-MODULE_LICENSE("GPL");
-
-MODULE_ALIAS_CRYPTO("crc32");
-MODULE_ALIAS_CRYPTO("crc32-pclmul");
deleted file mode 100644
@@ -1,249 +0,0 @@
-// SPDX-License-Identifier: GPL-2.0-only
-/*
- * Using hardware provided CRC32 instruction to accelerate the CRC32 disposal.
- * CRC32C polynomial:0x1EDC6F41(BE)/0x82F63B78(LE)
- * CRC32 is a new instruction in Intel SSE4.2, the reference can be found at:
- * http://www.intel.com/products/processor/manuals/
- * Intel(R) 64 and IA-32 Architectures Software Developer's Manual
- * Volume 2A: Instruction Set Reference, A-M
- *
- * Copyright (C) 2008 Intel Corporation
- * Authors: Austin Zhang <austin_zhang@linux.intel.com>
- * Kent Liu <kent.liu@intel.com>
- */
-#include <linux/init.h>
-#include <linux/module.h>
-#include <linux/string.h>
-#include <linux/kernel.h>
-#include <crypto/internal/hash.h>
-#include <crypto/internal/simd.h>
-
-#include <asm/cpufeatures.h>
-#include <asm/cpu_device_id.h>
-#include <asm/simd.h>
-
-#define CHKSUM_BLOCK_SIZE 1
-#define CHKSUM_DIGEST_SIZE 4
-
-#define SCALE_F sizeof(unsigned long)
-
-#ifdef CONFIG_X86_64
-#define CRC32_INST "crc32q %1, %q0"
-#else
-#define CRC32_INST "crc32l %1, %0"
-#endif
-
-#ifdef CONFIG_X86_64
-/*
- * use carryless multiply version of crc32c when buffer
- * size is >= 512 to account
- * for fpu state save/restore overhead.
- */
-#define CRC32C_PCL_BREAKEVEN 512
-
-asmlinkage u32 crc32c_x86_3way(u32 crc, const u8 *buffer, size_t len);
-#endif /* CONFIG_X86_64 */
-
-static u32 crc32c_intel_le_hw_byte(u32 crc, unsigned char const *data, size_t length)
-{
- while (length--) {
- asm("crc32b %1, %0"
- : "+r" (crc) : "rm" (*data));
- data++;
- }
-
- return crc;
-}
-
-static u32 __pure crc32c_intel_le_hw(u32 crc, unsigned char const *p, size_t len)
-{
- unsigned int iquotient = len / SCALE_F;
- unsigned int iremainder = len % SCALE_F;
- unsigned long *ptmp = (unsigned long *)p;
-
- while (iquotient--) {
- asm(CRC32_INST
- : "+r" (crc) : "rm" (*ptmp));
- ptmp++;
- }
-
- if (iremainder)
- crc = crc32c_intel_le_hw_byte(crc, (unsigned char *)ptmp,
- iremainder);
-
- return crc;
-}
-
-/*
- * Setting the seed allows arbitrary accumulators and flexible XOR policy
- * If your algorithm starts with ~0, then XOR with ~0 before you set
- * the seed.
- */
-static int crc32c_intel_setkey(struct crypto_shash *hash, const u8 *key,
- unsigned int keylen)
-{
- u32 *mctx = crypto_shash_ctx(hash);
-
- if (keylen != sizeof(u32))
- return -EINVAL;
- *mctx = le32_to_cpup((__le32 *)key);
- return 0;
-}
-
-static int crc32c_intel_init(struct shash_desc *desc)
-{
- u32 *mctx = crypto_shash_ctx(desc->tfm);
- u32 *crcp = shash_desc_ctx(desc);
-
- *crcp = *mctx;
-
- return 0;
-}
-
-static int crc32c_intel_update(struct shash_desc *desc, const u8 *data,
- unsigned int len)
-{
- u32 *crcp = shash_desc_ctx(desc);
-
- *crcp = crc32c_intel_le_hw(*crcp, data, len);
- return 0;
-}
-
-static int __crc32c_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
- u8 *out)
-{
- *(__le32 *)out = ~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
- return 0;
-}
-
-static int crc32c_intel_finup(struct shash_desc *desc, const u8 *data,
- unsigned int len, u8 *out)
-{
- return __crc32c_intel_finup(shash_desc_ctx(desc), data, len, out);
-}
-
-static int crc32c_intel_final(struct shash_desc *desc, u8 *out)
-{
- u32 *crcp = shash_desc_ctx(desc);
-
- *(__le32 *)out = ~cpu_to_le32p(crcp);
- return 0;
-}
-
-static int crc32c_intel_digest(struct shash_desc *desc, const u8 *data,
- unsigned int len, u8 *out)
-{
- return __crc32c_intel_finup(crypto_shash_ctx(desc->tfm), data, len,
- out);
-}
-
-static int crc32c_intel_cra_init(struct crypto_tfm *tfm)
-{
- u32 *key = crypto_tfm_ctx(tfm);
-
- *key = ~0;
-
- return 0;
-}
-
-#ifdef CONFIG_X86_64
-static int crc32c_pcl_intel_update(struct shash_desc *desc, const u8 *data,
- unsigned int len)
-{
- u32 *crcp = shash_desc_ctx(desc);
-
- /*
- * use faster PCL version if datasize is large enough to
- * overcome kernel fpu state save/restore overhead
- */
- if (len >= CRC32C_PCL_BREAKEVEN && crypto_simd_usable()) {
- kernel_fpu_begin();
- *crcp = crc32c_x86_3way(*crcp, data, len);
- kernel_fpu_end();
- } else
- *crcp = crc32c_intel_le_hw(*crcp, data, len);
- return 0;
-}
-
-static int __crc32c_pcl_intel_finup(u32 *crcp, const u8 *data, unsigned int len,
- u8 *out)
-{
- if (len >= CRC32C_PCL_BREAKEVEN && crypto_simd_usable()) {
- kernel_fpu_begin();
- *(__le32 *)out = ~cpu_to_le32(crc32c_x86_3way(*crcp, data, len));
- kernel_fpu_end();
- } else
- *(__le32 *)out =
- ~cpu_to_le32(crc32c_intel_le_hw(*crcp, data, len));
- return 0;
-}
-
-static int crc32c_pcl_intel_finup(struct shash_desc *desc, const u8 *data,
- unsigned int len, u8 *out)
-{
- return __crc32c_pcl_intel_finup(shash_desc_ctx(desc), data, len, out);
-}
-
-static int crc32c_pcl_intel_digest(struct shash_desc *desc, const u8 *data,
- unsigned int len, u8 *out)
-{
- return __crc32c_pcl_intel_finup(crypto_shash_ctx(desc->tfm), data, len,
- out);
-}
-#endif /* CONFIG_X86_64 */
-
-static struct shash_alg alg = {
- .setkey = crc32c_intel_setkey,
- .init = crc32c_intel_init,
- .update = crc32c_intel_update,
- .final = crc32c_intel_final,
- .finup = crc32c_intel_finup,
- .digest = crc32c_intel_digest,
- .descsize = sizeof(u32),
- .digestsize = CHKSUM_DIGEST_SIZE,
- .base = {
- .cra_name = "crc32c",
- .cra_driver_name = "crc32c-intel",
- .cra_priority = 200,
- .cra_flags = CRYPTO_ALG_OPTIONAL_KEY,
- .cra_blocksize = CHKSUM_BLOCK_SIZE,
- .cra_ctxsize = sizeof(u32),
- .cra_module = THIS_MODULE,
- .cra_init = crc32c_intel_cra_init,
- }
-};
-
-static const struct x86_cpu_id crc32c_cpu_id[] = {
- X86_MATCH_FEATURE(X86_FEATURE_XMM4_2, NULL),
- {}
-};
-MODULE_DEVICE_TABLE(x86cpu, crc32c_cpu_id);
-
-static int __init crc32c_intel_mod_init(void)
-{
- if (!x86_match_cpu(crc32c_cpu_id))
- return -ENODEV;
-#ifdef CONFIG_X86_64
- if (boot_cpu_has(X86_FEATURE_PCLMULQDQ)) {
- alg.update = crc32c_pcl_intel_update;
- alg.finup = crc32c_pcl_intel_finup;
- alg.digest = crc32c_pcl_intel_digest;
- }
-#endif
- return crypto_register_shash(&alg);
-}
-
-static void __exit crc32c_intel_mod_fini(void)
-{
- crypto_unregister_shash(&alg);
-}
-
-module_init(crc32c_intel_mod_init);
-module_exit(crc32c_intel_mod_fini);
-
-MODULE_AUTHOR("Austin Zhang <austin.zhang@intel.com>, Kent Liu <kent.liu@intel.com>");
-MODULE_DESCRIPTION("CRC32c (Castagnoli) optimization using Intel Hardware.");
-MODULE_LICENSE("GPL");
-
-MODULE_ALIAS_CRYPTO("crc32c");
-MODULE_ALIAS_CRYPTO("crc32c-intel");
@@ -36,10 +36,14 @@ lib-$(CONFIG_ARCH_HAS_COPY_MC) += copy_mc.o copy_mc_64.o
lib-$(CONFIG_INSTRUCTION_DECODER) += insn.o inat.o insn-eval.o
lib-$(CONFIG_RANDOMIZE_BASE) += kaslr.o
lib-$(CONFIG_FUNCTION_ERROR_INJECTION) += error-inject.o
lib-$(CONFIG_MITIGATION_RETPOLINE) += retpoline.o
+obj-$(CONFIG_CRC32_ARCH) += crc32-x86.o
+crc32-x86-y := crc32-glue.o crc32-pclmul.o
+crc32-x86-$(CONFIG_64BIT) += crc32c-3way.o
+
obj-y += msr.o msr-reg.o msr-reg-export.o hweight.o
obj-y += iomem.o
ifeq ($(CONFIG_X86_32),y)
obj-y += atomic64_32.o
new file mode 100644
@@ -0,0 +1,112 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * x86-optimized CRC32 functions
+ *
+ * Copyright (C) 2008 Intel Corporation
+ * Copyright 2012 Xyratex Technology Limited
+ * Copyright 2024 Google LLC
+ */
+
+#include <asm/cpufeatures.h>
+#include <asm/simd.h>
+#include <crypto/internal/simd.h>
+#include <linux/crc32.h>
+#include <linux/linkage.h>
+#include <linux/module.h>
+
+/* minimum size of buffer for crc32_pclmul_le_16 */
+#define CRC32_PCLMUL_MIN_LEN 64
+
+static DEFINE_STATIC_KEY_FALSE(have_crc32);
+static DEFINE_STATIC_KEY_FALSE(have_pclmulqdq);
+
+u32 crc32_pclmul_le_16(u32 crc, const u8 *buffer, size_t len);
+
+u32 crc32_le_arch(u32 crc, const u8 *p, size_t len)
+{
+ if (len >= CRC32_PCLMUL_MIN_LEN + 15 &&
+ crypto_simd_usable() && static_branch_likely(&have_pclmulqdq)) {
+ size_t n = -(uintptr_t)p & 15;
+
+ /* align p to 16-byte boundary */
+ if (n) {
+ crc = crc32_le_base(crc, p, n);
+ p += n;
+ len -= n;
+ }
+ n = round_down(len, 16);
+ kernel_fpu_begin();
+ crc = crc32_pclmul_le_16(crc, p, n);
+ kernel_fpu_end();
+ p += n;
+ len -= n;
+ }
+ if (len)
+ crc = crc32_le_base(crc, p, len);
+ return crc;
+}
+EXPORT_SYMBOL(crc32_le_arch);
+
+#ifdef CONFIG_X86_64
+#define CRC32_INST "crc32q %1, %q0"
+#else
+#define CRC32_INST "crc32l %1, %0"
+#endif
+
+/*
+ * Use carryless multiply version of crc32c when buffer size is >= 512 to
+ * account for FPU state save/restore overhead.
+ */
+#define CRC32C_PCLMUL_BREAKEVEN 512
+
+asmlinkage u32 crc32c_x86_3way(u32 crc, const u8 *buffer, size_t len);
+
+u32 crc32c_le_arch(u32 crc, const u8 *p, size_t len)
+{
+ size_t num_longs;
+
+ if (!static_branch_likely(&have_crc32))
+ return crc32c_le_base(crc, p, len);
+
+ if (IS_ENABLED(CONFIG_X86_64) && len >= CRC32C_PCLMUL_BREAKEVEN &&
+ crypto_simd_usable() && static_branch_likely(&have_pclmulqdq)) {
+ kernel_fpu_begin();
+ crc = crc32c_x86_3way(crc, p, len);
+ kernel_fpu_end();
+ return crc;
+ }
+
+ for (num_longs = len / sizeof(unsigned long);
+ num_longs != 0; num_longs--, p += sizeof(unsigned long))
+ asm(CRC32_INST : "+r" (crc) : "rm" (*(unsigned long *)p));
+
+ for (len %= sizeof(unsigned long); len; len--, p++)
+ asm("crc32b %1, %0" : "+r" (crc) : "rm" (*p));
+
+ return crc;
+}
+EXPORT_SYMBOL(crc32c_le_arch);
+
+u32 crc32_be_arch(u32 crc, const u8 *p, size_t len)
+{
+ return crc32_be_base(crc, p, len);
+}
+EXPORT_SYMBOL(crc32_be_arch);
+
+static int __init crc32_x86_init(void)
+{
+ if (boot_cpu_has(X86_FEATURE_XMM4_2))
+ static_branch_enable(&have_crc32);
+ if (boot_cpu_has(X86_FEATURE_PCLMULQDQ))
+ static_branch_enable(&have_pclmulqdq);
+ return 0;
+}
+arch_initcall(crc32_x86_init);
+
+static void __exit crc32_x86_exit(void)
+{
+}
+module_exit(crc32_x86_exit);
+
+MODULE_DESCRIPTION("x86-optimized CRC32 functions");
+MODULE_LICENSE("GPL");
similarity index 100%
rename from arch/x86/crypto/crc32-pclmul_asm.S
rename to arch/x86/lib/crc32-pclmul.S
similarity index 100%
rename from arch/x86/crypto/crc32c-pcl-intel-asm_64.S
rename to arch/x86/lib/crc32c-3way.S
@@ -2,11 +2,10 @@
config ISCSI_TARGET
tristate "SCSI Target Mode Stack"
depends on INET
select CRYPTO
select CRYPTO_CRC32C
- select CRYPTO_CRC32C_INTEL if X86
help
Say M to enable the SCSI target mode stack. A SCSI target mode stack
is software that makes local storage available over a storage network
to a SCSI initiator system. The supported storage network technologies
include iSCSI, Fibre Channel and the SCSI RDMA Protocol (SRP).