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    SubjectRe: [PATCH 3/6] x86: Add nopv parameter to disable PV extensions
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    On 23.06.19 15:01, Zhenzhong Duan wrote:
    > In virtualization environment, PV extensions (drivers, interrupts,
    > timers, etc) are enabled in the majority of use cases which is the
    > best option.
    >
    > However, in some cases (kexec not fully working, benchmarking)
    > we want to disable PV extensions. As such introduce the
    > 'nopv' parameter that will do it.
    >
    > There is already 'xen_nopv' parameter for XEN platform but not for
    > others. 'xen_nopv' can then be removed with this change.
    >
    > Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com>
    > Cc: xen-devel@lists.xenproject.org
    > ---
    > Documentation/admin-guide/kernel-parameters.txt | 4 ++++
    > arch/x86/kernel/cpu/hypervisor.c | 11 +++++++++++
    > 2 files changed, 15 insertions(+)
    >
    > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
    > index 138f666..b352f36 100644
    > --- a/Documentation/admin-guide/kernel-parameters.txt
    > +++ b/Documentation/admin-guide/kernel-parameters.txt
    > @@ -5268,6 +5268,10 @@
    > improve timer resolution at the expense of processing
    > more timer interrupts.
    >
    > + nopv= [X86]
    > + Disables the PV optimizations forcing the guest to run
    > + as generic guest with no PV drivers.
    > +
    > xirc2ps_cs= [NET,PCMCIA]
    > Format:
    > <irq>,<irq_mask>,<io>,<full_duplex>,<do_sound>,<lockup_hack>[,<irq2>[,<irq3>[,<irq4>]]]
    > diff --git a/arch/x86/kernel/cpu/hypervisor.c b/arch/x86/kernel/cpu/hypervisor.c
    > index 479ca47..4f2c875 100644
    > --- a/arch/x86/kernel/cpu/hypervisor.c
    > +++ b/arch/x86/kernel/cpu/hypervisor.c
    > @@ -85,10 +85,21 @@ static void __init copy_array(const void *src, void *target, unsigned int size)
    > to[i] = from[i];
    > }
    >
    > +static bool nopv;
    > +static __init int xen_parse_nopv(char *arg)

    You really don't want to use the "xen_" prefix here.


    Juergen

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