On Mon, 14 Jun 2010, Ramya Desai wrote: > Dear All, > > As a part of my driver testing instead of using sg lists I am directly > submitting the URB after merging all the sgs into a single URB buffer > in usb-storage driver. While converting the sg address into virtual > address (sg_virt(sg)) I am seeing 0, sometimes. Why am I seeing this > return value? If a page is located in high memory then it doesn't have a virtual address. Therefore sg_virt() has to return 0. > I have seen some comments about it, in usb_sg_init() function which is > defined in driver/usb/message.c file. In this routine also, sg_virt() > is used, however there is PageHighMem(sg_page(sg)) condition in there. > > Should I disable the CONFIG_HIGHMEM in the kernel while building the > kernel images? Or you could simply boot with mem=900M on the kernel command line. Alan Stern -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
