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In the mid-1980s Microsoft developed a multitasking version of DOS.
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relay_open(9) [centos man page]

RELAY_OPEN(9)						      relay interface support						     RELAY_OPEN(9)

NAME
relay_open - create a new relay channel SYNOPSIS
struct rchan * relay_open(const char * base_filename, struct dentry * parent, size_t subbuf_size, size_t n_subbufs, struct rchan_callbacks * cb, void * private_data); ARGUMENTS
base_filename base name of files to create, NULL for buffering only parent dentry of parent directory, NULL for root directory or buffer subbuf_size size of sub-buffers n_subbufs number of sub-buffers cb client callback functions private_data user-defined data DESCRIPTION
Returns channel pointer if successful, NULL otherwise. Creates a channel buffer for each cpu using the sizes and attributes specified. The created channel buffer files will be named base_filename0...base_filenameN-1. File permissions will be S_IRUSR. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 RELAY_OPEN(9)

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DEBUGFS_CREATE_BOOL(9)					      The debugfs filesystem					    DEBUGFS_CREATE_BOOL(9)

NAME
debugfs_create_bool - create a debugfs file that is used to read and write a boolean value SYNOPSIS
struct dentry * debugfs_create_bool(const char * name, umode_t mode, struct dentry * parent, u32 * value); ARGUMENTS
name a pointer to a string containing the name of the file to create. mode the permission that the file should have parent a pointer to the parent dentry for this file. This should be a directory dentry if set. If this parameter is NULL, then the file will be created in the root of the debugfs filesystem. value a pointer to the variable that the file should read to and write from. DESCRIPTION
This function creates a file in debugfs with the given name that contains the value of the variable value. If the mode variable is so set, it can be read from, and written to. This function will return a pointer to a dentry if it succeeds. This pointer must be passed to the debugfs_remove function when the file is to be removed (no automatic cleanup happens if your module is unloaded, you are responsible here.) If an error occurs, NULL will be returned. If debugfs is not enabled in the kernel, the value -ENODEV will be returned. It is not wise to check for this value, but rather, check for NULL or !NULL instead as to eliminate the need for #ifdef in the calling code. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 DEBUGFS_CREATE_BOOL(9)

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