Messages in this thread | | | From | Kay Sievers <> | Date | Mon, 13 Feb 2012 20:30:37 +0100 | Subject | Re: No /dev/root with devtmpfs? |
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On Mon, Feb 13, 2012 at 19:48, H. Peter Anvin <hpa@zytor.com> wrote: > On 02/13/2012 12:25 AM, Kirill Smelkov wrote: >>> >>> The bootloader might pass the root partition to the kernel via the >>> "root=" kernel parameter; these can be read at /proc/cmdline. >>> For example, on an HP iPAQ hx4700: root=/dev/mtdblock2 >> >> This does not work universally either, for example for >> >> root=PARTUUID=00112233-4455-6677-8899-AABBCCDDEEFF >> >> >> the kernel scans partitions and finds one for root by partition uuid >> (see name_to_dev_t() in init/do_mounts.c). >> >> That's exactly my situation - I have universal flash image which can >> bee booted via CF slot (on several boards, thus will have different >> /dev/hd? or /dev/sd?) and via usb/cardreader (again different /dev/ >> entry), and root is mounted by partition id. >> >> The kernel has no problem finding root partition and mounting it. I just >> needed a sane and robust way to know its choice. > > In this case it's not the kernel, but the initramfs which does this > lookup.
root=PARTUUID= is in-kernel mount GTP support, which works without an initramfs.
> In that case the initramfs could/should create /dev/root.
We dropped all that in initramfs for the earlier in this thread mentioned reasons.
/dev/root is not what we want, or what tools should expect to be there today; it will not work with modern filesystems, which have no single-device relationship.
Kay -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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