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/* libguestfs
* Copyright (C) 2009-2020 Red Hat Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* The appliance choice of CPU model.
*/
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include "guestfs.h"
#include "guestfs-internal.h"
/**
* Return the right CPU model to use as the qemu C<-cpu> parameter or
* its equivalent in libvirt. This returns:
*
* =over 4
*
* =item C<"host">
*
* The literal string C<"host"> means use C<-cpu host>.
*
* =item some string
*
* Some string such as C<"cortex-a57"> means use C<-cpu cortex-a57>.
*
* =item C<NULL>
*
* C<NULL> means no C<-cpu> option at all. Note returning C<NULL>
* does not indicate an error.
*
* =back
*
* This is made unnecessarily hard and fragile because of two stupid
* choices in QEMU:
*
* =over 4
*
* =item *
*
* The default for C<qemu-system-aarch64 -M virt> is to emulate a
* C<cortex-a15> (WTF?).
*
* =item *
*
* We don't know for sure if KVM will work, but C<-cpu host> is broken
* with TCG, so we almost always pass a broken C<-cpu> flag if KVM is
* semi-broken in any way.
*
* =back
*/
const char *
guestfs_int_get_cpu_model (int kvm)
{
#if defined(__aarch64__)
/* With -M virt, the default -cpu is cortex-a15. Stupid. */
if (kvm)
return "host";
else
return "cortex-a57";
#elif defined(__powerpc64__)
/* See discussion in https://bugzilla.redhat.com/show_bug.cgi?id=1605071 */
return NULL;
#else
/* On most architectures, it is faster to pass the CPU host model to
* the appliance, allowing maximum speed for things like checksums
* and encryption. Only do this with KVM. It is broken in subtle
* ways on TCG, and fairly pointless when you're emulating anyway.
*/
if (kvm)
return "host";
else
return NULL;
#endif
}
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