Re: Question about uhci-hcd's resource
Alan Stern <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
On Wed, 3 Oct 2007, jidong xiao wrote: > I saw uhci-hcd is not appearing at /proc/iomem, it only use ioports, > so does this mean uhci-hcd never allocate/map io memory? That's right. > but if it > doesn't allocate iomem, how to access its host memory? I don't understand your question. It sounds like you are asking how uhci-hcd can access the computer's memory, which doesn't make sense (uhci-hcd accesses the computer's memory the same way as any other part of the kernel, by executing MOV instructions). Are you asking how uhci-hcd accesses the controller's memory? It doesn't. All communication takes place over ioports, not by memory access. Are you asking how the controller accesses the computer's memory? It uses DMA. Alan Stern ------------------------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Still grepping through log files to find problems? Stop. Now Search log events and configuration files using AJAX and a browser. Download your FREE copy of Splunk now >> http://get.splunk.com/ _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel