hardware abstraction layer

This chapter describes the HAL, called the hardware abstract layer, which is the hardware abstraction tier, which is a set of libraries built on Linux drivers, and library is not part of the Linux kernel, but rather belongs to the application layer on top of the Linux kernel

generally placed under the two paths "/SYSTEM/LIB/HW" and "/VENDOR/LIB/HW".2. The name of the dynamic library is named "Id.variant.so", where the ID is provided on the upper layer and the variant name in the middle variant is changed with the system platform.Then, from 29 to 32 rows we can see whether the package name is found in "id.default.so" when all variants of the variant name form are not present.37 Rows, if (I The above rules of the HAL

1.HAL (handerware abstraction layer, hardware abstraction layer) is a set of libraries built on Linux programs that are not part of the kernel, but that belong to the application layer on top of the kernel.2. Reasons to join Hal i

: device is not open .");Return;}Hello_device-> set_val (hello_device, Val );} Static jint hello_getval (jnienv * EVN, jobject clazz){Int val = 0;If (! Hello_device ){Alogi ("Hello JNI: device is not open .");Return val;}Hello_device-> get_val (hello_device, Val ); Alogi ("Hello JNI: Get value % d to device.", Val ); Return val;}/* Open the interface of the hardware module defined in the hardware

Nineth Hardware Abstraction Layer: HALThe Nineth chapter mainly introduces a set of library HAL (Hardware abstraction Layer) built on Linux driver. This library is not part of the Linux kernel, but rather belongs to the applicatio

9th chapter: Hardware Abstraction Layer HAL1.HAL (Hardware abstraction layers, Hardware abstraction layer) is a set of flip fonts built on L

HAL (Hardware abstraction layer, hardware abstraction tier) is a set of libraries built on Linux drivers. This library is not part of the Linux kernel, but rather belongs to the application layer on top of the Linux kernel layer.T

ObjectiveRecently in Reading Luo Shenyang's "Android system source code scenario analysis," I believe that many people who engage in Android will go to see the book, then for the second chapter of the hardware abstraction layer, contact the actual work, it is necessary to learn something to do a summary analysis. Of course, this part will be based on Lao Luo's bo

In this section we examine the hardware abstraction layer: Halhal, a set of libraries built on Linux drivers. Just started to introduce why to add HAL to Android, the purpose is three, one, unified hardware call interface. Second, solve the GPL copyright issue. Third, for some special requirements. You can use the HAL

The HAL hardware abstraction layer is a set of libraries built on Linux drivers. belongs to the application layer on the Linux kernel layer. The main purpose of HAL is to avoid direct access to the Linux driver for the application and to protect "private property". Tradition

This chapter describes the-HAL(Hardware abstraction layer), a set of libraries built on Linux drivers. It is not part of the Linux kernel, but rather belongs to the application layer on top of the Linux kernel layer. In order to meet the requirements of these Linux drivers

requirementsSecond, HAL ArchitectureCompared to the old HAL schema, the new HAL schema adds some architectural requirements to the Ingress code, and a layer of service libraries (the HAL Library is located on this layer by ID).Note: Although the new HAL schema is used, the old HAL schema is still supported for compatibility.Iii. steps to write Linux drivers that support HAL1. Write Linux drivers (Linux dri

This chapter focuses on the hardware abstraction layer: HAL, which is a set of libraries built on Linux drivers. Just started to introduce why to add HAL to Android, the purpose is three, one, unified hardware call interface. Second, solve the GPL copyright issue. Third, for some special requirements. You can use the H

Here are the main problems encountered two: the first is that the HAL layer of the source code to add to the Android default compilation, that is, in the root directory to do make, their own HAL source code will be compiled. The second problem is that after the compilation is complete, it is automatically installed under the specified system directory LIB/HW.At first, you don't know much, you always need to use MMM to compile and install, but it's unr

Hal is a set of programs built on Linux drivers. This library is not part of the Linux kernel, but rather belongs to the application layer on top of the Linux kernel layer. The main purpose of adding HAL is to protect "private property" in addition to trying to avoid direct access to Linux drives by the application. So how is it protected?The HAL is located at the Android System Runtime

HAL(Hardware abstraction layer) is built onLinuxa set of main programs above the driver, which does not belong toLinuxkernel, but belongs toLinuxthe application layer above the kernel layer,Googleto beAndroidIncreaseHALThe main purpose of the test is to avoid direct access t

bytes of data. 6. Because the LED driver's device file receives not a string, but a byte type of data, it is necessary to do a separate program to the device file to write byte-form data, or to read the byte-type data from the device file. 7.HAL modules can be automatically called by the Android system, and naturally have interfaces like the main or init functions. Except that this interface is not a function, but a fixed-name struct-body variable hal_module_info_sym. in other words, all the H

requirements.Android HAL Architecture. The rationale is to use the library (. so file) in the Android system to invoke Linux drivers located in kernel space (typically accessed through device files). The android application (apk file) can then access the library in the HAL through the NDK program, or access the library in the HAL directly from the Android application. The new version adds the entry code for the HAL schema that is required by the HAL architecture.Added HAL for LED driver.1 to wr

character device array in the kernel;(4) Create struct classwith class_creat macro;(5) Create a device file using the device_create function;2.uninstalling the Led driver's device files3. Set register and initialize led driver4, control led lights:(1) control LED via string (2) control via I/o command5 . Module parameters of LED driver6. Test LED driver(1) A general program for writing test I/O control commands;(2) using NDK to test LED driver;(3) using Java test LED driver;7,Led Drive transp

: There are two storage paths for HAL library files:/SYSTEM/LIB/HW and/VENDOR/LIB/HW. The Hw_get_module function looks for the library file from the/SYSTEM/LIB/HW directory based on the library file naming rules. If the library file is not found in the/SYSTEM/LIB/HW directory, the hw_get_ module will look in the/VENDOR/LIB/HW directory as the same rule.The naming convention for HAL Module library files is ID.suffix.so. Where the ID is specified by the ID parameter of the hw_get_ module func