Messages in this thread | | | From | "H. Peter Anvin" <> | Subject | Re: 64-bit kdev_t - just for playing | Date | 2 Apr 2003 14:03:58 -0800 |
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Followup to: <200304020931.38671.pbadari@us.ibm.com> By author: Badari Pulavarty <pbadari@us.ibm.com> In newsgroup: linux.dev.kernel > > Roman, > > Here is the patch for sd to allow more than 256 disks. > There are few issues with the patch that need to be resolved. > > 1) With the patch I get 16 bits for minor. Since 4 bits are used for > partition, we get 12 bits to represent disks. So each major can support > 2^12 =3D 4096 disks. Disks 0 - 4095 are mapped to major=3D8,=20 > disks 4096 - 8191 to major =3D 65 and so on.. > > This means .. > > (i) I need to create nodes in /dev/ to match new <major, minor> for=20 > these disks. Currently "mknod" is broken due to glibc issues with dev_t. > > (ii) We need to worry about backward compatibility. For example: > 17th disk used to have <65, 0>. Now its major, minor is <8, 256>. > So /dev/ entires need to be re-created to match these, everytime > you reboot 2.4/2.5 etc. Greg KH udev might fix this for us.=20 > > 2) Do we still need 16 majors for disks ? >
No, we don't. On the other hand, we really should change to 64 partitions/disk, same as for non-SCSI disks. 16 really is too small.
-hpa
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