Re: recent head having significantly less "avail memory"

From: Konstantin Belousov <kostikbel_at_gmail.com>
Date: Mon, 13 Sep 2021 17:08:25 UTC 
On Mon, Sep 13, 2021 at 02:59:25PM +0200, Guido Falsi via freebsd-current wrote:
> Hi,
> 
> I updated head recently and today I noticed a difference which looks wrong.
> 
> At boodt the new head shows signifcantly less avail memory than before,
> around 3 GiB less.
> 
> I moved from commit 71fbc6faed6 [1] where I got:
> 
> Aug 28 22:03:03 marvin kernel: real memory  = 17179869184 (16384 MB)
> Aug 28 22:03:03 marvin kernel: avail memory = 16590352384 (15821 MB)
> 
> to commit 7955efd574b [2] where I get:
> 
> Sep 13 10:44:40 marvin kernel: real memory  = 17179869184 (16384 MB)
> Sep 13 10:44:40 marvin kernel: avail memory = 13298876416 (12682 MB)
> 
> I'm seeing this on multiple machines.
> 
> Unluckily bisecting and trying an older loader.efi in sseparate tests did
> not give me any more insight.
> 
> The recent changes to efi loader, starting with commit 6032b6ba9596 [3] look
> like a possible trigger to this, but I have been unable to confirm it.
> 
> Any suggesstions on how to proceed to debug thiss? ANy idea what a fix could
> be?

Is this UEFI or bios boot?
Provide verbose dmesg for old and new boots on the same machine.
For UEFI boot, show output of 'sysctl machdep.efi_map', again for old
and new boots.