DMA (Direct Memory Access) controller access implementation method for Loongson blade large-memory address devices

Abstract

The invention provides a DMA controller access implementation method for Loongson blade large-memory address devices. A management control module applies for a 256M address space in a memory; when a DMA controller and an address space lower than 32 bits carry out data transmission, data are transmitted according to the conventional DMA transmission mode; when the DMA controller and an address space higher than 32 bits carry out data transmission, the DMA controller sends an access address to an address-parsing module, the address-parsing module parses and then sends the address to an address conversion module, the address conversion module converts the address, and a mapping module carries out memory mapping according to the address converted by the address conversion module to map the address higher than 32 bits into the memory for which the management control module applies in advance. The method effectively solves the problem that a 32-bit Loongson CPU (central processing unit) cannot support memories exceeding the 32-bit address, and thereby the Loongson CPU can use a 64-bit address space at most.

Description

technical field [0001] The present invention relates to a method for supporting a large memory of a Loongson blade, specifically, a method for realizing access to a DMA controller of a Loongson blade large memory address device Background technique [0002] At present, the device address is generally 32 bits. If the device is in the case of DMA data transmission with the memory, the device will not be recognized when the memory address is greater than 32 bits. So some methods are needed to solve this problem. The Linux kernel version requires a pass The data cache to the storage device must be placed in the low-end memory area of ​​the physical RAM, even if the application can use both high-end memory and low-end memory at the same time. In this way, I / O requests from the data cache in the low-end memory area can directly perform memory access operations. However, when the application issues an I / O request that includes a data cache located in high memory, the kernel will f...

AI Technical Summary

Problems solved by technology

However, the current Loongson products do not support large memory, so in order to implement Loongson blades, it is necessary to support large memory