用户空间可以通过DMA_BUF_IOCTL_SYNC ioctl使用这些标记。该序列将如下使用: mmap dma-buf fd 对于CPU中的每个绘制/上传周期 1. SYNC_START ioctl,2. 读/写到mmap区域 3. SYNC_END ioctl。这可以重复进行(新数据被GPU或扫描设备消耗)。 一旦不再需要缓冲区,可以进行munmap。 为了正确性和最佳性能,在访问映射地...
dma-buf: Update docs for SYNC ioctl Just a bit of wording polish plus mentioning that it can fail and must be restarted. Requested by Sumit. v2: Fix them typos (Hans). Cc: Chris Wilson <chris@chris-wilson.co.uk> Cc: Tiago Vignatti <tiago.vignatti@intel.com> Cc: Stéphane Marchesin ...
EDIT: Description has been rewritten as the initial test case was incorrect. Waypipe (package, workaround) relies on DMA_BUF_IOCTL_SYNC to check if a given file descripter is backed by DMABUF. On FreeBSD the ioctl always fails with EBADF...
} struct dma_buf_sync sync; sync.flags = DMA_BUF_SYNC_START | DMA_BUF_SYNC_END; // 设置同步标志 sync.offset = 0; // 设置偏移量 sync.size = 4096; // 设置大小 int ret = ioctl(fd, DMA_BUF_IOCTL_SYNC, &sync); // 调用ioctl设置DMA传输参数 if (ret < 0) { perror("ioctl"); ...
This commit from NXP's gst-plugins-base fork states that DMA_BUF_IOCTL_SYNC should not be used because "it causes issue".
coherency, DMA_BUF_IOCTL_SYNC must be used to bracket* any CPU access to give the kernel the chance to shuffle memory around if* needed.** Prior to accessing the map, the client must call DMA_BUF_IOCTL_SYNC* with DMA_BUF_SYNC_START and the appropriate read/write flags. Once the* ...
*//* 休眠 */wait_event_interruptible(dma_waitq,ev_dma);if(memcmp(src,dst,BUF_SIZE)==0){printk("MEM_CPY_DMA OK\n");}else{printk("MEM_CPY_DMA ERROR\n");}break;}}return0;}staticstructfile_operationsdma_fops={.owner=THIS_MODULE,.ioctl=s3c_dma_ioctl,};staticirqreturn_ts3c_dma_irq...
int(*sync)(struct vm_area_struct *vma,unsigned long,size_t,unsigned int flags); 这个方法被msync系统调用以将一个脏的内存区段保存到存贮介质上。如果成功则返回值为0 ,如果有错,则返回一个负数。核心版本1.2让这个方法返回void,因为这个函数不被认为会失败。
int(*sync)(struct vm_area_struct *vma,unsigned long,size_t,unsigned int flags); 这个方法被msync系统调用以将一个脏的内存区段保存到存贮介质上。如果成功则返回值为0 ,如果有错,则返回一个负数。核心版本1.2让这个方法返回void,因为这个函数不被认为会失败。
int(*sync)(struct vm_area_struct *vma,unsigned long,size_t,unsigned int flags); 这个方法被msync系统调用以将一个脏的内存区段保存到存贮介质上。如果成功则返回值为0 ,如果有错,则返回一个负数。核心版本1.2让这个方法返回void,因为这个函数不被认为会失败。