Subject: Re: Flag days (was re: Re: NODEVMTIME kernel option gone, replaced
To: DAVID RANKIN <email@example.com>
From: Bill Studenmund <skippy@macro.Stanford.EDU>
Date: 12/02/1998 14:24:47
On Wed, 2 Dec 1998, DAVID RANKIN wrote:
> On a somewhat related flag day note, how much of a flag day would changing
> major and minor sizes cause? As part of the startup for an LVM driver for
> NetBSD, I'm trying to figure out how to get the driver to tell the device
> files for each logical volume. On most OSes with LVMs, they use 8 bits
> of the minor number to hold the logical volume number, and then 4 or more
> bits to identify the LV's volume group.
> >From what I've seen, NetBSD uses an 8 bit major and an 8 bit minor,
> which means that I have to use something other than the minor number to
> tell the difference between 255 logical volumes * X volume groups.
> What kind of pain would be involved to a move to either 16 bit major numbers
> and 16 bit minor numbers, or even 8 bit major/24 bit minors numbers like
> HP and others use?
Uhm, NetBSD currently has 12 bit major and 20 bit minor devices.
What we haven't done is switch DISKUNIT and DISKPART to use more than 8
or 16 bits for subunits.
You should be able to just make your own macros to split the minor fields
up as you wish.