Subject: Re: Options MEMORY_DISK_SERVER
To: None <>
From: Perry E. Metzger <>
List: tech-kern
Date: 12/30/2007 12:40:30
Joerg Sonnenberger <> writes:
> On Sun, Dec 30, 2007 at 12:22:02PM -0500, Perry E. Metzger wrote:
>> Joerg Sonnenberger <> writes:
>> > how much does that option still make sense and do we need it for the
>> > install floppies? Compressed netbsd kernel diff is 100 byte on AMD64,
>> > so would just dropping it overflow floppies on other platforms?
>> Could you refresh our memories on what the option does? I once
>> understood this well, but it has been some years since I did the SSTO
>> install system (i.e. our current installer on x86) and I no longer
>> remember all the details.
> It skips some code I think for the userland to control memory disk. It
> is only set for the install floppies and I don't think it is required
> for them.

Ah, it is documented in options(4)...

     options MEMORY_DISK_SERVER=0
     Do not include the interface to a userland memory disk server process.
     Per default, this option is set to 1, including the support code.  Useful
     for install media kernels.

The option saves a teeny bit of memory, but as you note, it is not
required for the install floppies, it is just a way of making them a
few hundred bytes smaller. I can't really say if it will break the
i386 stuff by making the floppies too large, but you are correct that
the only effect of removing the option will be to make the floppies
larger -- it has no other function.

My opinion is that we need longer term solutions to the problem of
install media size, and that we should not be sweating over a few
hundred bytes.

Perry E. Metzger