9.1 minimal ram requirements

[Ian Smith]

On Sun, 23 Dec 2012 15:21:23 +0300, Sergey Kandaurov wrote:
 > On 23 December 2012 10:22, Ian Smith <smithi at nimnet.asn.au> wrote:
 > > On Sun, 23 Dec 2012 03:45:39 +0300, Sergey Kandaurov wrote:
 > >  > This (i.e. the "kmem_map too small" message seen with kernel memory
 > >  > shortage) could be due to CAM CTL ('device ctl' added in 9.1), which is
 > >  > quite a big kernel memory consumer.
 > >  > Try to disable CTL in loader with kern.cam.ctl.disable=1 to finish boot.
 > >
 > > I've just added that, thanks Sergey, but it's sadly not an option for
 > > installation.  I guess it's too late for the release notes - which at
 > > RC3 made no mention of CAM CTL at all - but it's not yet clear to me
 > > whether even 256MB is enough to boot, install and run 9.1 GENERIC?
 > 
 > If you perform clean installation (e.g. from ISO), you can escape to the
 > loader prompt and set the tunable there w/o the need for /boot/loader.conf.
 > I experimented with Vbox and AFAIK 256MB was enough even with CAM CTL.

Ah right; I'd booted and installed from memstick, where escape to loader 
prompt is not an option.  I'll burn a disc1 and try that with the 128MB 
again, and make sure that 256MB is comfortable - after holiday madness.

 > >  > A longer term workaround could be to postpone those memory allocations
 > >  > until the first call to CTL.

That would seem to make sense, while making it a module is still on the 
todo list.  I guess there must be systems that need CAM CTL to boot?

 > > Under what circumstances is CAM CTL needed?  What would leaving it out
 > > of GENERIC cost, and whom?  Is it loadable?  dmesg.boot reports loading,
 > > but I don't see a module, nor can I find much information about CTL in
 > > cam(3|4) or /sys/conf/NOTES.  apropos found ctladm and ctlstat, but I'm
 > > little the wiser as to when it may be needed, beyond CAM/SCSI debugging?
 > 
 > The purpose and current status are well documented in the initial commit
 > message (r229997) and the supplied README.ctl.txt. To my modest knowledge,
 > it should be safe to just comment out 'device ctl' in GENERIC.

Thanks for the reference, seems that I won't be needing it just now; it 
just wasn't clear to me what if any other subsystems might hang off it.

cheers, Ian