Date: Wed, 9 Aug 2006 17:12:47 -0400 From: John Baldwin <jhb@freebsd.org> To: "Jin Guojun [VFFS]" <j_guojun@lbl.gov> Cc: Julian Stacey <jhs@berklix.org>, freebsd-hardware@freebsd.org Subject: Re: Real and available memory? Message-ID: <200608091712.48401.jhb@freebsd.org> In-Reply-To: <44DA46D3.3040504@lbl.gov> References: <200608090908.k79988pY086073@fire.jhs.private> <200608091431.50183.jhb@freebsd.org> <44DA46D3.3040504@lbl.gov>
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On Wednesday 09 August 2006 16:34, Jin Guojun [VFFS] wrote: Please don't use HTML-only e-mail. >> Well, that's where the missing 40 meg is. :) The kernel text (including >> any modules and preloaded mfsroot's) aren't include in the 'avail memory' >> count. > > This is not where the memory goes. > The MFS root is probably not allocated yet at this point. Huh? Of course it is! You load it from /boot/loader into RAM at the same point when you load the kernel. All of the kernel text plus any loaded modules are not considered available memory when 'avail memory' is output. (Along with a few other pages needed for things like crashdumps, some VM bootstrapping data structures, etc.) You can't load a MFS root after the kernel is booted because if it's the root filesystem, there's no place for it to be loaded from once the kernel boots. -- John Baldwin
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