xentools415 build failure on NetBSD 9.99.90 amd64

["oskar%fessel.org@localhost" <oskar%fessel.org@localhost>]

Hello,

ist seems impossible to build xentools 415 on netbsd -current (also on 9.99.74 and 9.99.82)
Is nobody using that?
Any clue how to fix that?

Cheers
	Oskar
---
echo 'rel-1.14.0' > seabios-dir/.version
/usr/pkg/bin/gmake CC=gcc PYTHON=python3.9 subdirs-all
gmake[4]: Entering directory '/usr/pkgsrc/sysutils/xentools415/work/xen-4.15.1/tools/firmware'
gmake[5]: Entering directory '/usr/pkgsrc/sysutils/xentools415/work/xen-4.15.1/tools/firmware'
/usr/pkg/bin/gmake -C seabios-dir CC=gcc LD=ld PYTHON=python3.9 EXTRAVERSION="-Xen" all;
gmake[6]: Entering directory '/usr/pkgsrc/sysutils/xentools415/work/seabios-rel-1.14.0'
mkdir -p out//scripts/kconfig/lxdialog
mkdir -p out//include/config
mkdir -p out/src out/src/hw out/src/fw out/vgasrc
/usr/pkg/bin/gmake -C out/ -f /usr/pkgsrc/sysutils/xentools415/work/seabios-rel-1.14.0/scripts/kconfig/Makefile srctree=/usr/pkgsrc/sysutils/xentools415/work/seabios-rel-1.14.0 src=scripts/kconfig obj=scripts/kconfig Q= Kconfig=/usr/pkgsrc/sysutils/xentools415/work/seabios-rel-1.14.0/src/Kconfig  silentoldconfig
gmake[7]: Entering directory '/usr/pkgsrc/sysutils/xentools415/work/seabios-rel-1.14.0/out'
  Build Kconfig config file
mkdir -p include/config include/generated
scripts/kconfig/conf --silentoldconfig /usr/pkgsrc/sysutils/xentools415/work/seabios-rel-1.14.0/src/Kconfig
gmake[7]: Leaving directory '/usr/pkgsrc/sysutils/xentools415/work/seabios-rel-1.14.0/out'
  Compile checking out/src/misc.o
gcc -Iout/ -Isrc -Os -MD -g -Wall -Wno-strict-aliasing -Wold-style-definition -Wtype-limits -m32 -march=i386 -mregparm=3 -mpreferred-stack-boundary=2 -minline-all-stringops -fomit-frame-pointer -freg-struct-return -ffreestanding -fno-delete-null-pointer-checks -ffunction-sections -fdata-sections -fno-common -fno-merge-constants -fno-pie -fno-stack-protector -fstack-check=no -Wno-address-of-packed-member -fcf-protection=none -DMODE16=0 -DMODESEGMENT=0 -c src/misc.c -o out/src/misc.o
  Compile checking out/src/stacks.o
gcc -Iout/ -Isrc -Os -MD -g -Wall -Wno-strict-aliasing -Wold-style-definition -Wtype-limits -m32 -march=i386 -mregparm=3 -mpreferred-stack-boundary=2 -minline-all-stringops -fomit-frame-pointer -freg-struct-return -ffreestanding -fno-delete-null-pointer-checks -ffunction-sections -fdata-sections -fno-common -fno-merge-constants -fno-pie -fno-stack-protector -fstack-check=no -Wno-address-of-packed-member -fcf-protection=none -DMODE16=0 -DMODESEGMENT=0 -c src/stacks.c -o out/src/stacks.o
src/stacks.c: In function 'run_thread':
src/stacks.c:568:5: error: 'asm' operand has impossible constraints
  568 |     asm volatile(
      |     ^~~
gmake[6]: *** [Makefile:141: out/src/stacks.o] Error 1
gmake[6]: Leaving directory '/usr/pkgsrc/sysutils/xentools415/work/seabios-rel-1.14.0'
gmake[5]: *** [Makefile:138: subdir-all-seabios-dir] Error 2
gmake[5]: Leaving directory '/usr/pkgsrc/sysutils/xentools415/work/xen-4.15.1/tools/firmware'
gmake[4]: *** [/usr/pkgsrc/sysutils/xentools415/work/xen-4.15.1/tools/firmware/../../tools/Rules.mk:156: subdirs-all] Error 2
gmake[4]: Leaving directory '/usr/pkgsrc/sysutils/xentools415/work/xen-4.15.1/tools/firmware'
gmake[3]: *** [Makefile:37: all] Error 2
gmake[3]: Leaving directory '/usr/pkgsrc/sysutils/xentools415/work/xen-4.15.1/tools/firmware'
gmake[2]: *** [/usr/pkgsrc/sysutils/xentools415/work/xen-4.15.1/tools/../tools/Rules.mk:161: subdir-all-firmware] Error 2
gmake[2]: Leaving directory '/usr/pkgsrc/sysutils/xentools415/work/xen-4.15.1/tools'
gmake[1]: *** [/usr/pkgsrc/sysutils/xentools415/work/xen-4.15.1/tools/../tools/Rules.mk:156: subdirs-all] Error 2
gmake[1]: Leaving directory '/usr/pkgsrc/sysutils/xentools415/work/xen-4.15.1/tools'
gmake: *** [Makefile:63: build-tools] Error 2
*** Error code 2

Stop.
make[2]: stopped in /usr/pkgsrc/sysutils/xentools415
*** Error code 1

Stop.
make[1]: stopped in /usr/pkgsrc/sysutils/xentools415
*** Error code 1

Stop.
make: stopped in /usr/pkgsrc/sysutils/xentools415
netbsd-hell-2# uname -a
NetBSD netbsd-hell-2.fessel.org 9.99.90 NetBSD 9.99.90 (GENERIC) #0: Sun Oct  3 07:15:11 EEST 2021  root%netbsd-2gb-hel1-1.fessel.org@localhost:/usr/src/obj/sys/arch/amd64/compile/GENERIC amd64