[PATCH] SUPPORT.md: Explicitly desupport pvgrub1; and support grub-pv

[Ian Jackson <iwj@xxxxxxxxxxxxxx>]

We can no longer conveniently even test pv-grub1; osstest tests for
this have just been dropped from all Xen branches
(by osstest.git#8dee6e333622).

This is without prejudice to its eventual removal.  We should perhaps
proceed cautiously with that since it may be helpful for some old
guests.

Under the circumstances, I think this patch has to be a backport
candidate to all still-supported trees.

CC: Juergen Gross <jgross@xxxxxxxx>
CC: Jan Beulich <jbeulich@xxxxxxxx>,
CC: Wei Liu <wl@xxxxxxx>
Backport-requested-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>
Signed-off-by: Ian Jackson <iwj@xxxxxxxxxxxxxx>
---
 SUPPORT.md | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/SUPPORT.md b/SUPPORT.md
index 317392d8f3..9db027a85f 100644
--- a/SUPPORT.md
+++ b/SUPPORT.md
@@ -832,6 +832,28 @@ OVMF firmware implements the UEFI boot protocol.
 
     Status, qemu-xen: Supported
 
+### grub-pv aka pvgrub2 (guest bootloader)
+
+    Status: Supported
+
+Support in upstream GRUB2 for running in Xen PV, to booting Xen PV
+guests.
+
+Collaboration (and security coordination) and fixes will be provided
+by the Xen Project, as needed.
+
+### x86/HVM pvgrub1 (aka stubdom pv-grub)
+
+    Status: Obsolescent, limited support
+
+GRUB1 compiled with minios and Xen stubdom, to run in guest context.
+This is provided in the Xen source distribution for the benefit of
+very old guests; it is no longer tested, but build and functionality
+fixes are welcome.
+
+pvgrub1 is not security-supported.  However, it runs in guest context,
+so there should be no implications for host security.
+
 # Format and definitions
 
 This file contains prose, and machine-readable fragments.
-- 
2.20.1