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blk_queue_bounce_limit(9) [centos man page]

BLK_QUEUE_BOUNCE_LIM(9) 					   Block Devices					   BLK_QUEUE_BOUNCE_LIM(9)

blk_queue_bounce_limit - set bounce buffer limit for queue SYNOPSIS
void blk_queue_bounce_limit(struct request_queue * q, u64 dma_mask); ARGUMENTS
q the request queue for the device dma_mask the maximum address the device can handle DESCRIPTION
Different hardware can have different requirements as to what pages it can do I/O directly to. A low level driver can call blk_queue_bounce_limit to have lower memory pages allocated as bounce buffers for doing I/O to pages residing above dma_mask. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 BLK_QUEUE_BOUNCE_LIM(9)

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DEVICE(9) Device drivers infrastructure STRUCT DEVICE(9) NAME
struct_device - The basic device structure SYNOPSIS
struct device { struct device * parent; struct device_private * p; struct kobject kobj; const char * init_name; const struct device_type * type; struct mutex mutex; struct bus_type * bus; struct device_driver * driver; void * platform_data; struct dev_pm_info power; struct dev_pm_domain * pm_domain; #ifdef CONFIG_PINCTRL struct dev_pin_info * pins; #endif #ifdef CONFIG_NUMA int numa_node; #endif u64 * dma_mask; u64 coherent_dma_mask; struct device_dma_parameters * dma_parms; struct list_head dma_pools; struct dma_coherent_mem * dma_mem; #ifdef CONFIG_CMA #endif struct dev_archdata archdata; struct device_node * of_node; struct acpi_dev_node acpi_node; dev_t devt; u32 id; spinlock_t devres_lock; struct list_head devres_head; struct klist_node knode_class; struct class * class; const struct attribute_group ** groups; void (* release) (struct device *dev); bool offline_disabled:1; bool offline:1; }; MEMBERS
parent The device's "parent" device, the device to which it is attached. In most cases, a parent device is some sort of bus or host controller. If parent is NULL, the device, is a top-level device, which is not usually what you want. p Holds the private data of the driver core portions of the device. See the comment of the struct device_private for detail. kobj A top-level, abstract class from which other classes are derived. init_name Initial name of the device. type The type of device. This identifies the device type and carries type-specific information. mutex Mutex to synchronize calls to its driver. bus Type of bus device is on. driver Which driver has allocated this platform_data Platform data specific to the device. power For device power management. See Documentation/power/devices.txt for details. pm_domain Provide callbacks that are executed during system suspend, hibernation, system resume and during runtime PM transitions along with subsystem-level and driver-level callbacks. pins For device pin management. See Documentation/pinctrl.txt for details. numa_node NUMA node this device is close to. dma_mask Dma mask (if dma'ble device). coherent_dma_mask Like dma_mask, but for alloc_coherent mapping as not all hardware supports 64-bit addresses for consistent allocations such descriptors. dma_parms A low level driver may set these to teach IOMMU code about segment limitations. dma_pools Dma pools (if dma'ble device). dma_mem Internal for coherent mem override. archdata For arch-specific additions. of_node Associated device tree node. acpi_node Associated ACPI device node. devt For creating the sysfs "dev". id device instance devres_lock Spinlock to protect the resource of the device. devres_head The resources list of the device. knode_class The node used to add the device to the class list. class The class of the device. groups Optional attribute groups. release Callback to free the device after all references have gone away. This should be set by the allocator of the device (i.e. the bus driver that discovered the device). offline_disabled If set, the device is permanently online. offline Set after successful invocation of bus type's .offline. EXAMPLE
For devices on custom boards, as typical of embedded and SOC based hardware, Linux often uses platform_data to point to board-specific structures describing devices and how they are wired. That can include what ports are available, chip variants, which GPIO pins act in what additional roles, and so on. This shrinks the "Board Support Packages" (BSPs) and minimizes board-specific #ifdefs in drivers. DESCRIPTION
At the lowest level, every device in a Linux system is represented by an instance of struct device. The device structure contains the information that the device model core needs to model the system. Most subsystems, however, track additional information about the devices they host. As a result, it is rare for devices to be represented by bare device structures; instead, that structure, like kobject structures, is usually embedded within a higher-level representation of the device. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 STRUCT DEVICE(9)
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