Re: Clarifying PVH mode requirements

["Roger Pau Monné" <roger.pau@citrix.com>]

El 31/01/16 a les 22.27, PGNet Dev ha escrit:
> I run Xen 4.6 Dom0
> 
>     rpm -qa | egrep -i "kernel-default-4|xen-4"
>         kernel-default-devel-4.4.0-8.1.g9f68b90.x86_64
>         xen-4.6.0_08-405.1.x86_64

Are your kernels compiled with CONFIG_PVH enabled?

> My guests are currently HVM in PVHVM mode; I'm exploring PVH.
> 
> IIUC, for 4.6, this doc
> 
>     http://xenbits.xen.org/docs/4.6-testing/misc/pvh-readme.txt
> 
> instructs the following necessary changes:
> 
> @ GRUBG cfg
> 
> -    GRUB_CMDLINE_XEN=" ..."
> +    GRUB_CMDLINE_XEN=" dom0pvh ..."
> 
> &, @ guest.cfg
> 
> +    pvh = 1
> 
> For my guest.cfg, currently in PVHVM mode, I have
> 
>     builder = 'hvm'
>     xen_platform_pci = 1
>     device_model_version="qemu-xen"
>     hap = 1
>     ...
> 
> Q:
>     Do any of these^^ params need to also change with the addition of
> 
>     pvh = 1

Yes, you need to remove builder, xen_platform_pci and
device_model_version, and add a kernel and ramdisk parameters that point
to the actual kernel and ramdisk that you want to use. The file should
look like:

kernel = "/path/to/kernel"
ramdisk = "/path/to/ramdisk"
pvh=1
hap=1

[... other options, memory, vcpus ...]

The paths in the kernel and ramdisk options are relative to Dom0, not
DomU. You can also use pygrub if you prefer, by removing the
kernel/ramdisk options and setting the bootloader one:

bootloader="pygrub"

> 
>> At the moment HAP is required for PVH.
> 
> As above, I've 'hap = 1' enabled.
> 
> But checking cpu,
> 
>     hwinfo --cpu | egrep "Arch|Model"
>       Arch: X86-64
>       Model: 6.60.3 "Intel(R) Xeon(R) CPU E3-1220 v3 @ 3.10GHz"

You CPU is perfectly capable of running both a PVH Dom0 or DomU, check:

http://ark.intel.com/products/52269/Intel-Xeon-Processor-E3-1220-8M-Cache-3_10-GHz

Look for EPT and VT-d which are the main requirements for PVH.

> Q:
>     Am I out of luck re: PVH with more modern Haswell? Or is there a
> different check I should be running ?
> 
>> At present the only PVH guest is an x86 64bit PV linux.
> 
> Is this still current/true info?

IIRC Boris (CCed) added support for 32bit PVH to Linux, so you should be
able to use either 32 or 64 kernels.

Roger.