铝合金窗什么品牌好:pmem杂记

froyo:

drivers/misc/pmem.c

frameworks/base/libs/binder:

这是一个简单的使用：

pmem_fd = open("/dev/pmem_adsp", O_RDWR, 0);//打开设备，为了操作硬件引擎，要noncache的
ioctl(pmem_fd, PMEM_GET_TOTAL_SIZE, ®ion)  //获取全部空间

pmem_base = mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, pmem_fd, 0);//mmap操作

ioctl(pmem_fd, PMEM_GET_PHYS, ®ion) //获取物理地址

munmap

考虑使用PMEM_CONNECT的话，有
1。 multiple references with multiple allocations

fd0 = open("/dev/pmem_xxx", ...)

mmap();

...

fd1 = open("/dev/pmem_xxx", ...)

mmap();

2。 multiple references with one allocation in oneprocess or one process group

fd0 = open("/dev/pmem_xxx", ...)

mmap();

...

fd1 = open("/dev/pmem_xxx", ...);

ret = ioctl(fd1, PMEM_CONNECT, fd0);

if (ret != 0) goto error;

struct pmem_region region1 = { offset1, size1 };

ret = ioctl(fd1, PMEM_MAP, ®ion1);

...

3. multiple references with one allocation inmultiple processes

a think it's a little tricky 

MemoryHeapBase

MemoryHeapBase ：BnMemoryHeap

MemoryHeapPmem ：MemoryHeapBase

MemoryHeapPmem ::MemoryPmem :BnMemory :BnInterface

view plainprint?

1.        struct pmem_region region;  
2. sp base = new MemoryHeapBase(PMEM_DEVICE,  
3.     mPreviewFrameSize_align * (kPreviewBufCnt));  
4. if (base->heapID() < 0) {  
5.     LOGE("Failed to allocate pmem from %s", PMEM_DEVICE);  
6. }  
7. mPreviewHeap = new MemoryHeapPmem(base, 0);  
8. int fd_pmem = mPreviewHeap->getHeapID();  
9. if (ioctl(fd_pmem, PMEM_GET_PHYS, ®ion)) {  
10.     LOGE("%s: Failed to get PMEM physical address", __FUNCTION__);  
11. }  
12.   
13.       /* 
14.        * Make an IMemory for each streaming buffer so that we can reuse 
15.        * them in callbacks. 
16.        */  
17.       for (int i = 0; i < kPreviewBufCnt; i++) {  
18.           mBuffers[i] = (static_cast(mPreviewHeap.get()))->  
19.               mapMemory(i * mPreviewFrameSize_align, mPreviewFrameSize);  
20.           mBufferPhyAddr[i] = (void *)(region.offset +  
21.                                        i * mPreviewFrameSize_align);  
22.       }