The installer considers a disk a root disk if 'a' is FFS and contains
expected files.
Furthermore, unattended upgrades will always install to the first root
disk that is found.
This works fine on machines with only one root disk, but it quickly
behaves unexpectedly when having multiple disks/installations in one
machine.
I run such machines, esp. since fiddling with softraid and installboot.
The installer/sysupgrade experience can definitely be improved here, but
that takes some consideration.
One requirement, imho, is knowing
1. which disk we booted from, i.e.
from which disk the kernel (/bsd.rd or /bsd.upgrade) was loaded
2. which disk the root filesystem is on, i.e.
likely the same disk holding /home where sysupgrade put the sets
The boot disk could be helpful inside installer, e.g. to check if
/bsd.ugpraded was booted from a valid root disk -- a good indicator for
rebooting from the same disk the user just ran sysupgrade on.
The root disk is of no help inside the installer as that will always be
the ramdisk. But it could be used by sysupgrade to perhaps prefill
/auto_upgrade.conf to decide up-front which disk to upgrade.
This answer to the 'Which disk is the root disk' question is currently
answered inside the installer during unattended upgrades... and it will
always be the first valid root disk, which is not always correct.
So to make progress, here's a diff that exports readily available
disklabel DUIDs:
# disklabel sd0 | grep duid
duid: 98c0c47c3ffddeb4
# sysctl hw | grep duid
hw.bootduid=98c0c47c3ffddeb4
hw.rootduid=98c0c47c3ffddeb4
Having that, working out the installer/sysupgrade bits should be easier.
I'm testing this on arm64 with two disks/installations.
Feedback? Objection? OK?
Index: kern/kern_sysctl.c
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/kern/kern_sysctl.c,v
retrieving revision 1.406
diff -u -p -r1.406 kern_sysctl.c
--- kern/kern_sysctl.c 16 Aug 2022 13:29:52 -0000 1.406
+++ kern/kern_sysctl.c 5 Sep 2022 09:51:38 -0000
@@ -762,6 +762,12 @@ hw_sysctl(int *name, u_int namelen, void
case HW_SMT:
return (sysctl_hwsmt(oldp, oldlenp, newp, newlen));
#endif
+ case HW_BOOTDUID:
+ return (sysctl_rdstring(oldp, oldlenp, newp,
+ duid_format(bootduid)));
+ case HW_ROOTDUID:
+ return (sysctl_rdstring(oldp, oldlenp, newp,
+ duid_format(rootduid)));
default:
return sysctl_bounded_arr(hw_vars, nitems(hw_vars), name,
namelen, oldp, oldlenp, newp, newlen);
Index: sys/sysctl.h
===================================================================
RCS file: /mount/openbsd/cvs/src/sys/sys/sysctl.h,v
retrieving revision 1.229
diff -u -p -r1.229 sysctl.h
--- sys/sysctl.h 16 Aug 2022 13:29:53 -0000 1.229
+++ sys/sysctl.h 5 Sep 2022 09:53:13 -0000
@@ -931,7 +931,9 @@ struct kinfo_file {
#define HW_SMT 24 /* int: enable SMT/HT/CMT */
#define HW_NCPUONLINE 25 /* int: number of cpus being
used */
#define HW_POWER 26 /* int: machine has wall-power
*/
-#define HW_MAXID 27 /* number of valid hw ids */
+#define HW_BOOTDUID 27 /* string: DUID of boot disk */
+#define HW_ROOTDUID 28 /* string: DUID of root disk */
+#define HW_MAXID 29 /* number of valid hw ids */
#define CTL_HW_NAMES { \
{ 0, 0 }, \
@@ -961,6 +963,8 @@ struct kinfo_file {
{ "smt", CTLTYPE_INT }, \
{ "ncpuonline", CTLTYPE_INT }, \
{ "power", CTLTYPE_INT }, \
+ { "bootduid", CTLTYPE_STRING }, \
+ { "rootduid", CTLTYPE_STRING }, \
}
/*
