Hi Grant, On Tue, Nov 20, 2012 at 2:32 PM, Grant Likely <grant.lik...@secretlab.ca> wrote: > On Tue, Nov 20, 2012 at 10:23 PM, Simon Glass <s...@chromium.org> wrote: >> Hi, >> >> I hope this is a stupid question with an easy answer, but I cannot find it. >> >> I have a device tree node for an mmc block device and I want to use >> that block device from another driver. I have a phandle which lets me >> get the node of the mmc device, but I am not sure how to convert that >> into a block_device. In order to do so, I think I need a major/minor >> number. Of course the phandle might in fact point to a SCSI driver and >> I want that to work correctly also. >> >> I imagine I might be able to search through the wonders of sysfs in >> user space, but is there a better way? > > Do you /want/ to do it from userspace? What is your use case? Mounting > the rootfs?
The use case is storing some raw data on a block device from within a driver in the kernel. It is used to keep track of the verified boot state. > > Regardless, userspace can monitor the uevents when devices are added > (that's what udev does) and watch for the full path of the node you > want in the uevent attribute. Then you can look for the child device > with the block major/minor numbers in it. So is there a way to do this entirely in the kernel ex post? It might need to happen during kernel boot, before user space. > > g. Thanks, Simon -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
