Re: Warning: FreeBSD using its (in partition) SWAP space when running under Parallels on aarch64 macOS (M4 MAX)

On Feb 19, 2025, at 05:38, Olivier Certner <[email protected]> wrote:

> Hi Mark,
> 
>> Something I possibly should have done --but did not do was to set:
>> kern.hz=100
>> in /boot/loader.conf (or anywhere).
> 
> Barring explicitly setting this tunable, the kernel automatically defaults to a kern.hz of 100 (HZ_VM) when it detects it runs in a virtual machine.  That detection is currently performed by the smbios(4) driver, which is supposed to handle Parallels and is compiled in by arm64's GENERIC, so I assume you have actually been running with kern.hz set to 100 already.

It only handles the amd64(/i386) Parallels smbios case. ARM Parallels is different.

sys/dev/smbios/smbios_subr.c has:

static const struct {
       const char      *vm_pname;
       int             vm_guest;
} vm_pnames[] = {
       { "VMware Virtual Platform",    VM_GUEST_VMWARE },
       { "Virtual Machine",            VM_GUEST_VM }, /* Microsoft VirtualPC */
       { "QEMU Virtual Machine",       VM_GUEST_VM },
       { "VirtualBox",                 VM_GUEST_VBOX },
       { "Parallels Virtual Platform", VM_GUEST_PARALLELS },
       { "KVM",                        VM_GUEST_KVM },
};

but on an M4 MAX macOS system with FreeBSD under Parallels,
FreeBSD reports:

# kenv smbios.system.product
Parallels ARM Virtual Machine

Thus under aarch64 Parallels FreeBSD reports:

# sysctl kern.vm_guest
kern.vm_guest: none

# sysctl kern.hz
kern.hz: 1000

(The above is copied from another Email that I sent out
later yesterday.)

> The result of:
> sysctl kern.hz kern.vm_guest
> inside your VM should say where we actually stand.
> 

aarch64 FreeBSD has no clue that it is running in a VM.


===
Mark Millard
marklmi at yahoo.com