Hello,
I’m trying to use vdispl interface from PV OS, it doesn’t work.
Configuration details:
Xen 4.12.1
Dom0: Linux 4.20.17-gentoo #13 SMP Sat Dec 28 11:12:24 MSK 2019 x86_64
Intel(R) Celeron(R) CPU N3050 @ 1.60GHz GenuineIntel GNU/Linux
DomU: x86 Plan9, PV
displ_be as a backend for vdispl and vkb
when VM starts, displ_be reports about an error:
gnttab: error: ioctl DMABUF_EXP_FROM_REFS failed: Invalid argument
(displ_be.log:221)
related Dom0 output is:
[ 191.579278] Cannot provide dma-buf: use_ptemode 1 (dmesg.create.log:123)
According to the linux kernel sources use_ptemod is:
gntdev.c:1213: use_ptemod = !xen_feature(XENFEAT_auto_translated_physmap);
But xen-features.pl script doesn't show this feature is set for Dom0:
Xen features: 000028f0
enabled: pae_pgdir_above_4gb
enabled: mmu_pt_update_preserve_ad
enabled: dom0
enabled: memory_op_vnode_supported
According to the Xen sources, auto_translated_physmap is set up in a case of :
xen/common/kernel.c:467: if ( paging_mode_translate(d) )
xen/common/kernel.c-468- fi.submap |=
xen/common/kernel.c-469- (1U <<
XENFEAT_writable_page_tables) |
xen/common/kernel.c-470- (1U <<
XENFEAT_auto_translated_physmap);
where
xen/include/asm-x86/paging.h:73:#define paging_mode_translate(_d)
(!!((_d)->arch.paging.mode & PG_translate))
But PG_translate is applied only for HVM, at least I have not fount any other
points:
xen/arch/x86/hvm/hvm.c:606: rc = paging_enable(d,
PG_refcounts|PG_translate|PG_external);
What configuration should be for vdispl is able to work?
Or maybe I can to something to make Xen set auto_translated_physmap feature up
to continue using of vdispl?
And should I make any special support for the feature in PV OS?
All logs and configs are attached.
Thanks in advance.
Best regards,
Alexander Sychev
logs.tar.gz
Description: GNU Zip compressed data
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