Messages in this thread | | | Date | Sat, 29 May 1999 02:14:32 +0200 (MET DST) | From | (Guest section DW) | Subject | Re: Migrating to larger numbers |
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> dev_t: 32 bits minimum, suggest 64 bits
> Recall that uid_t, gid_t and dev_t both have -1 (0xffff) reserved > in a 16-bit environment;
This suggests a particular way of going to a larger dev_t.
I have been using (and am using a kernel like this right now):
static inline kdev_t to_kdev_t(dev_t dev) { int major, minor;
major = (dev >> 32); if (!major) { major = (dev >> 16); if (!major) { major = (dev >> 8); minor = (dev & 0xff); } else minor = (dev & 0xffff); } else minor = (dev & 0xffffffff);
return MKDEV(major, minor); }
I am not aware of any disadvantages of this system, although, now that I think about it, the fact that multiple representations yield the same (major,minor) has both advantages and disadvantages. So far I have not encountered real problems.
Andries
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