On Tue, 5 Feb 2008, Pete Zaitcev wrote: > The problem stems from the fact that usbmon's hooks may not have > access to the virtual address of the data. On cache-coherent > architectures, such as x86, usbmon works around it by remapping > data temporarily. I think the problem should be transparent if > you look at the code in and around usb_hcd_submit_urb(). > > You can change usb-storage to not pre-map commands and replies > easily, but data often comes from the highmem zone and thus > kernel does not have its virtual address.
In such cases the page number is stored in a scatter-gather entry. Should we modify the core to keep a copy of the page number in the URB, for use by mon_dmapeek()? Of course, this could be confusing. If an URB is pre-mapped for DMA, then usbmon wouldn't know whether to look in the transfer_buffer field for the virtual address or in the new page-number field. Sometimes neither might be valid. Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
