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Peter Anvin" , lkml , X86 ML References: <20260805082137.1214967-1-jgross@suse.com> <20260805082137.1214967-5-jgross@suse.com> <5febc2c0-4355-48d9-9342-52d590041500@suse.com> Content-Language: en-US From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-purgate-ID: tlsNG-c201ff/1785923717-732B32A1-0584B9CF/0/0 X-purgate-type: clean X-purgate-size: 2699 On 05.08.2026 11:44, Jürgen Groß wrote: > On 05.08.26 11:04, Jan Beulich wrote: >> On 05.08.2026 10:55, Juergen Gross wrote: >>> On 05.08.26 10:44, Jan Beulich wrote: >>>> On 05.08.2026 10:21, Juergen Gross wrote: >>>>> --- a/arch/x86/xen/Makefile >>>>> +++ b/arch/x86/xen/Makefile >>>>> @@ -37,8 +37,8 @@ obj-$(CONFIG_XEN_PVH) += enlighten_pvh.o >>>>> obj-$(CONFIG_EVENT_TRACING) += trace.o >>>>> >>>>> obj-$(CONFIG_SMP) += smp.o >>>>> +obj-$(CONFIG_SMP) += smp_hvm.o >>>>> obj-$(CONFIG_XEN_PV_SMP) += smp_pv.o >>>>> -obj-$(CONFIG_XEN_PVHVM_SMP) += smp_hvm.o >>>> >>>> Similar issue here - in a PV-only config smp_hvm.o doesn't want / shouldn't >>>> need building. >>> >>> Note that I didn't change any functionality. >>> >>> I agree that it seems a little bit strange, but in the end I believe >>> the current status is okay-ish. PV-only hasn't been something in upstream >>> Linux since Xen support was added, as PV was always meant to be an >>> alternative to bare metal support via paravirt patching. It might have >>> been possible to build a kernel not really functional on bare metal, but >>> this was more like the ability to build a x86 kernel not working on any >>> existing machine. >>> >>> IMO the Xen kernel config options should allow for adding Xen-specific >>> features, but minimum Xen support should always have basic HVM support, >>> which includes the Xen specific performance enhancements. >> >> I fear I don't understand this. If I want a kernel just to run as PV Dom0, >> why would it need to carry anything HVM-ish? That is (or should be) >> entirely unrelated to being able to also run this same kernel on baremetal >> then. > > The fact is that Xen PV-mode was always a feature not really liked especially > by x86 maintainers (this is the polite way to phrase it). > > Changing something outside of xen-specific parts of the kernel in favor of PV is > nearly always a fight and I'm pretty sure I only get changes in by playing nice > (not changing more than absolutely necessary and cleaning up constantly). I will > certainly not try to push for a "PV-only" kernel while the hope of the x86 > maintainers is more "PV will go away some time in future". > > The capability to configure the kernel without HVM stuff but with Xen support > is the way it has been since many years now. Nobody has missed a PV-only kernel, > so I conclude there is no need for that. Just FTR - I did, even if maybe I never said so explicitly. But as it's just me ... Jan > The closest we will get here is a PVH > only kernel, and this is possible by not enabling CONFIG_XEN_PVHVM_GUEST. > > > Juergen