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Re: [PATCH 0/2] xen: Fix PV-only build
- To: Juergen Gross <jgross@xxxxxxxx>, Jan Beulich <jbeulich@xxxxxxxx>
- From: Jason Andryuk <jason.andryuk@xxxxxxx>
- Date: Thu, 6 Aug 2026 09:58:32 -0400
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- Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxxx>, <linux-kernel@xxxxxxxxxxxxxxx>, "Stefano Stabellini" <sstabellini@xxxxxxxxxx>, Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx>, Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>, Thomas Gleixner <tglx@xxxxxxxxxx>, Ingo Molnar <mingo@xxxxxxxxxx>, Borislav Petkov <bp@xxxxxxxxx>, Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>, <x86@xxxxxxxxxx>, "H. Peter Anvin" <hpa@xxxxxxxxx>
- Delivery-date: Thu, 06 Aug 2026 13:58:49 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On 2026-08-06 09:31, Juergen Gross wrote:
On 06.08.26 15:24, Jason Andryuk wrote:
On 2026-08-06 08:00, Jürgen Groß wrote:
On 06.08.26 13:31, Jan Beulich wrote:
On 06.08.2026 12:55, Juergen Gross wrote:
On 06.08.26 03:52, Jason Andryuk wrote:
Allow disabling XEN_PVHVM for a PV-only. A stub in the event channel
code needs to be fixed first.
Jason Andryuk (2):
xen/events: Fix xen_set_upcall_vector stub
xen/Kconfig: select XEN_PVHVM
arch/x86/xen/Kconfig | 8 +++++---
drivers/xen/events/events_base.c | 2 +-
2 files changed, 6 insertions(+), 4 deletions(-)
I did a comparison of a kernel built with your patches disabling
XEN_PVHVM
and my patches with XEN_PVHVM_GUEST disabled.
The kernel built with my patches is 6 bytes smaller than the one
with your
patches.
Isn't this a sign of something else needing tweaking, somewhere?
This is a sign that there are probably only very few really HVM
specific paths
(in the sense of: explicitly not marked as irrelevant for PV) in the
kernel.
Yes, I'm sure you can find some more, but I'm really not sure this is
relevant
for more than a handful of users.
I see more reduction:
15029248 - arch/x86/boot/bzImage
15021056 - arch/x86/boot/bzImage.after
~8k
52542480 - vmlinux
52523184 - vmlinux.after
~18k
$ ../linux/scripts/bloat-o-meter vmlinux vmlinux.after
add/remove: 1/136 grow/shrink: 14/48 up/down: 15902/-22430 (-6528)
Did you disable CONFIG_XEN_PVHVM_GUEST in the before kernel, too?
Yes
$ grep PVHVM config-before config-after config-pvh-before:CONFIG_XEN_PVHVM=y
config-pvh-before:CONFIG_XEN_PVHVM_SMP=y
config-pvh-before:# CONFIG_XEN_PVHVM_GUEST is not set
config-pvh-after:# CONFIG_XEN_PVHVM_GUEST is not set
These three options change:
$ diff -u config-before config-after
-CONFIG_XEN_PVHVM=y
-CONFIG_XEN_PVHVM_SMP=y
-CONFIG_XEN_AUTO_XLATE=y
Regards,
Jason
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