Re: Making tmpfs reserved memory configurable

[Eduardo Horvath <eeh%NetBSD.org@localhost>]

On Fri, 30 May 2014, Martin Husemann wrote:

> See mount_tmpfs(8), in the paragraph about the -s option:
> 
>    Note that four megabytes are always reserved for the system and cannot
>    be assigned to the file system.
> 
> Now, with a 3.2 MB text GENERIC kernel and 8 MB RAM, we certainly don't have
> 4 MB available at all - so tmpfs is not usable.

This just doesn't sound right.  Why is tmpfs reserving a fixed amount of 
RAM?  Shouldn't it be using uvmexp.freemin?  That's basically what we're 
reserving for emergencies.

RAM scaling is always a pain in the posterior.  The choices made for a 
system with 16MB RAM don't make sense for a system with 16GB RAM, and visa 
versa.

Eduardo