xen: fix x86-64 boot and guest bundling issues

Fix several issues found during x86-64 Xen testing:

- xen-image-minimal: use -cpu host for KVM to avoid Xen CPUID
  filtering stripping AVX/AVX2 from x86-64-v3 builds, causing
  illegal instruction crashes in Dom0
- xen-image-minimal: use QB_MEM_VALUE (not QB_MEM) to properly
  override the hard assignment in qemuboot-xen-defaults.bbclass
- xen-image-minimal: set dom0_mem=512M via QB_XEN_CMDLINE_EXTRA
- qemuboot-xen-x86-64.cfg: add dom0_mem=512M to static syslinux
  config so guest autostart has memory available
- vgabios: use ${SAVANNAH_GNU_MIRROR} for reliable downloads
- alpine-xen-guest-bundle: add per-architecture checksums for
  aarch64 and x86_64 tarballs, fix S variable warning

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

1 files changed, 8 insertions, 2 deletions

diff --git a/recipes-extended/images/xen-image-minimal.bb b/recipes-extended/images/xen-image-minimal.bb
index 68b5b029..f4ab99d8 100644
--- a/recipes-extended/images/xen-image-minimal.bb
+++ b/recipes-extended/images/xen-image-minimal.bb
@@ -92,8 +92,14 @@ WKS_FILE:x86-64 = "directdisk-xen.wks"
 WKS_FILE_DEPENDS_DEFAULT:x86-64 = "syslinux-native"
 WKS_FILE:qemux86-64 = "qemuboot-xen-x86-64.wks"
 WKS_FILE_DEPENDS_DEFAULT:qemux86-64 = "syslinux-native"
-# Dom0 needs enough memory for containerd + vxn DomU management
-QB_MEM ?= "-m 1024"
+# Xen Dom0 needs the full host CPU feature set (AVX, AVX2, etc.) since
+# the machine default Skylake-Client model can lose features through Xen's
+# nested CPUID filtering, causing illegal instruction crashes with x86-64-v3.
+QB_CPU_KVM:qemux86-64 = "-cpu host -machine q35,i8042=off"
+# Dom0 needs enough memory for containerd + vxn DomU management.
+# QB_MEM_VALUE overrides the ??= default in qemuboot-xen-defaults;
+# QB_MEM itself is a hard assign in the class so ?= here won't work.
+QB_MEM_VALUE = "1024"
 QB_XEN_CMDLINE_EXTRA = "dom0_mem=512M"
 QB_DEFAULT_KERNEL ?= "none"
 QB_DEFAULT_FSTYPE ?= "wic"