# SPDX-License-Identifier: GPL-2.0-only
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config CIFS
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tristate "SMB3 and CIFS support (advanced network filesystem)"
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depends on INET
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select NLS
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select CRYPTO
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select CRYPTO_MD4
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select CRYPTO_MD5
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select CRYPTO_SHA256
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select CRYPTO_SHA512
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select CRYPTO_CMAC
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select CRYPTO_HMAC
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select CRYPTO_LIB_ARC4
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select CRYPTO_AEAD2
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select CRYPTO_CCM
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select CRYPTO_GCM
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select CRYPTO_ECB
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select CRYPTO_AES
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select CRYPTO_LIB_DES
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select KEYS
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help
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This is the client VFS module for the SMB3 family of NAS protocols,
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(including support for the most recent, most secure dialect SMB3.1.1)
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as well as for earlier dialects such as SMB2.1, SMB2 and the older
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Common Internet File System (CIFS) protocol. CIFS was the successor
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to the original dialect, the Server Message Block (SMB) protocol, the
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native file sharing mechanism for most early PC operating systems.
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The SMB3 protocol is supported by most modern operating systems
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and NAS appliances (e.g. Samba, Windows 10, Windows Server 2016,
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MacOS) and even in the cloud (e.g. Microsoft Azure).
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The older CIFS protocol was included in Windows NT4, 2000 and XP (and
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later) as well by Samba (which provides excellent CIFS and SMB3
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server support for Linux and many other operating systems). Use of
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dialects older than SMB2.1 is often discouraged on public networks.
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This module also provides limited support for OS/2 and Windows ME
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and similar very old servers.
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This module provides an advanced network file system client
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for mounting to SMB3 (and CIFS) compliant servers. It includes
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support for DFS (hierarchical name space), secure per-user
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session establishment via Kerberos or NTLM or NTLMv2, RDMA
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(smbdirect), advanced security features, per-share encryption,
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directory leases, safe distributed caching (oplock), optional packet
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signing, Unicode and other internationalization improvements.
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In general, the default dialects, SMB3 and later, enable better
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performance, security and features, than would be possible with CIFS.
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Note that when mounting to Samba, due to the CIFS POSIX extensions,
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CIFS mounts can provide slightly better POSIX compatibility
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than SMB3 mounts. SMB2/SMB3 mount options are also
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slightly simpler (compared to CIFS) due to protocol improvements.
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If you need to mount to Samba, Azure, Macs or Windows from this machine, say Y.
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config CIFS_STATS2
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bool "Extended statistics"
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depends on CIFS
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help
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Enabling this option will allow more detailed statistics on SMB
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request timing to be displayed in /proc/fs/cifs/DebugData and also
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allow optional logging of slow responses to dmesg (depending on the
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value of /proc/fs/cifs/cifsFYI, see fs/cifs/README for more details).
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These additional statistics may have a minor effect on performance
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and memory utilization.
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Unless you are a developer or are doing network performance analysis
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or tuning, say N.
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config CIFS_ALLOW_INSECURE_LEGACY
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bool "Support legacy servers which use less secure dialects"
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depends on CIFS
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default y
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help
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Modern dialects, SMB2.1 and later (including SMB3 and 3.1.1), have
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additional security features, including protection against
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man-in-the-middle attacks and stronger crypto hashes, so the use
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of legacy dialects (SMB1/CIFS and SMB2.0) is discouraged.
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Disabling this option prevents users from using vers=1.0 or vers=2.0
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on mounts with cifs.ko
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If unsure, say Y.
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config CIFS_WEAK_PW_HASH
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bool "Support legacy servers which use weaker LANMAN security"
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depends on CIFS && CIFS_ALLOW_INSECURE_LEGACY
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help
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Modern CIFS servers including Samba and most Windows versions
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(since 1997) support stronger NTLM (and even NTLMv2 and Kerberos)
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security mechanisms. These hash the password more securely
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than the mechanisms used in the older LANMAN version of the
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SMB protocol but LANMAN based authentication is needed to
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establish sessions with some old SMB servers.
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Enabling this option allows the cifs module to mount to older
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LANMAN based servers such as OS/2 and Windows 95, but such
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mounts may be less secure than mounts using NTLM or more recent
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security mechanisms if you are on a public network. Unless you
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have a need to access old SMB servers (and are on a private
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network) you probably want to say N. Even if this support
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is enabled in the kernel build, LANMAN authentication will not be
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used automatically. At runtime LANMAN mounts are disabled but
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can be set to required (or optional) either in
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/proc/fs/cifs (see fs/cifs/README for more detail) or via an
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option on the mount command. This support is disabled by
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default in order to reduce the possibility of a downgrade
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attack.
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If unsure, say N.
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config CIFS_UPCALL
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bool "Kerberos/SPNEGO advanced session setup"
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depends on CIFS
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select DNS_RESOLVER
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help
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Enables an upcall mechanism for CIFS which accesses userspace helper
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utilities to provide SPNEGO packaged (RFC 4178) Kerberos tickets
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which are needed to mount to certain secure servers (for which more
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secure Kerberos authentication is required). If unsure, say Y.
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config CIFS_XATTR
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bool "CIFS extended attributes"
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depends on CIFS
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help
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Extended attributes are name:value pairs associated with inodes by
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the kernel or by users (see the attr(5) manual page for details).
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CIFS maps the name of extended attributes beginning with the user
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namespace prefix to SMB/CIFS EAs. EAs are stored on Windows
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servers without the user namespace prefix, but their names are
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seen by Linux cifs clients prefaced by the user namespace prefix.
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The system namespace (used by some filesystems to store ACLs) is
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not supported at this time.
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If unsure, say Y.
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config CIFS_POSIX
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bool "CIFS POSIX Extensions"
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depends on CIFS && CIFS_ALLOW_INSECURE_LEGACY && CIFS_XATTR
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help
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Enabling this option will cause the cifs client to attempt to
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negotiate a newer dialect with servers, such as Samba 3.0.5
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or later, that optionally can handle more POSIX like (rather
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than Windows like) file behavior. It also enables
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support for POSIX ACLs (getfacl and setfacl) to servers
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(such as Samba 3.10 and later) which can negotiate
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CIFS POSIX ACL support. If unsure, say N.
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config CIFS_DEBUG
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bool "Enable CIFS debugging routines"
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default y
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depends on CIFS
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help
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Enabling this option adds helpful debugging messages to
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the cifs code which increases the size of the cifs module.
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If unsure, say Y.
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config CIFS_DEBUG2
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bool "Enable additional CIFS debugging routines"
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depends on CIFS_DEBUG
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help
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Enabling this option adds a few more debugging routines
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to the cifs code which slightly increases the size of
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the cifs module and can cause additional logging of debug
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messages in some error paths, slowing performance. This
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option can be turned off unless you are debugging
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cifs problems. If unsure, say N.
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config CIFS_DEBUG_DUMP_KEYS
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bool "Dump encryption keys for offline decryption (Unsafe)"
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depends on CIFS_DEBUG
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help
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Enabling this will dump the encryption and decryption keys
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used to communicate on an encrypted share connection on the
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console. This allows Wireshark to decrypt and dissect
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encrypted network captures. Enable this carefully.
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If unsure, say N.
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config CIFS_DFS_UPCALL
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bool "DFS feature support"
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depends on CIFS
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select DNS_RESOLVER
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help
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Distributed File System (DFS) support is used to access shares
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transparently in an enterprise name space, even if the share
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moves to a different server. This feature also enables
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an upcall mechanism for CIFS which contacts userspace helper
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utilities to provide server name resolution (host names to
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IP addresses) which is needed in order to reconnect to
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servers if their addresses change or for implicit mounts of
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DFS junction points. If unsure, say Y.
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config CIFS_NFSD_EXPORT
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bool "Allow nfsd to export CIFS file system"
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depends on CIFS && BROKEN
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help
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Allows NFS server to export a CIFS mounted share (nfsd over cifs)
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config CIFS_SMB_DIRECT
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bool "SMB Direct support"
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depends on CIFS=m && INFINIBAND && INFINIBAND_ADDR_TRANS || CIFS=y && INFINIBAND=y && INFINIBAND_ADDR_TRANS=y
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help
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Enables SMB Direct support for SMB 3.0, 3.02 and 3.1.1.
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SMB Direct allows transferring SMB packets over RDMA. If unsure,
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say Y.
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config CIFS_FSCACHE
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bool "Provide CIFS client caching support"
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depends on CIFS=m && FSCACHE || CIFS=y && FSCACHE=y
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help
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Makes CIFS FS-Cache capable. Say Y here if you want your CIFS data
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to be cached locally on disk through the general filesystem cache
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manager. If unsure, say N.
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config CIFS_ROOT
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bool "SMB root file system (Experimental)"
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depends on CIFS=y && IP_PNP
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help
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Enables root file system support over SMB protocol.
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Most people say N here.
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