features/cpulist_abbrev: Add "63" alias for "last"

Change-Id: Ie82d70f74f36f9c064411b2f8ef0a7391aee9284
Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>

2 files changed, 59 insertions, 0 deletions

diff --git a/features/cpulist_abbrev/0001-cpumask-Add-63-alias-for-last-in-cpu-list.patch b/features/cpulist_abbrev/0001-cpumask-Add-63-alias-for-last-in-cpu-list.patch
new file mode 100644
index 0000000..3ba61df
--- /dev/null
+++ b/features/cpulist_abbrev/0001-cpumask-Add-63-alias-for-last-in-cpu-list.patch
@@ -0,0 +1,58 @@
+From c52f05fb623b0e12c2c91aec6d02c7bd6f6cab0b Mon Sep 17 00:00:00 2001
+From: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
+Date: Tue, 6 Jul 2021 10:39:05 +0000
+Subject: [PATCH] cpumask: Add "63" alias for "last" in cpu list
+
+Enea Edge currently hardcodes the kernel args based on previous
+releases' contents, bringing in arguments like "isolcpus=1-63",
+which are no longer supported (the last CPU has to be a valid CPU
+number after [1, 2]).
+
+To work around this issue (at least until the proper mechanism is
+implemented to generate the correct kernel arguments), we have to
+deal with the "63" hardcoded value at the kernel level. Since "63"
+was actually meant to be the last CPU, treat "63" as just another
+token for "last" (since we don't currently support machines with
+more than 64 cores).
+
+This is a terrible workaround for a very complex issue on Enea
+Edge upgrade/downgrade via OSTree deployments and should be
+removed as soon as the proper mechanism for generating kernel args
+is in place.
+
+Upstream-Status: Inappropiate [Enea specific]
+
+[1] https://github.com/torvalds/linux/commit/e22cdc3f
+[2] https://github.com/torvalds/linux/commit/edb93821
+
+Signed-off-by: Alexandru Avadanii <Alexandru.Avadanii@enea.com>
+---
+ lib/cpumask.c | 9 +++++++++
+ 1 file changed, 9 insertions(+)
+
+diff --git a/lib/cpumask.c b/lib/cpumask.c
+index e4b8a8c252c7..6739a93b4c8d 100644
+--- a/lib/cpumask.c
++++ b/lib/cpumask.c
+@@ -211,9 +211,18 @@ int __ref cpulist_parse(const char *buf, struct cpumask *dstp)
+        /*
+         * bitmap_parselist has no concept of "last" CPU, so we have to
+         * replace "last" with a real number in dest copy of the string.
++        *
++        * ENEA_start
++        * Due to compatibility restrictions with kernel args imposed by earlier
++        * releases, we need to support cpulists in the form of "0-63". To keep
++        * it simple, we will just define "63" as an alias for "last", as we
++        * don't support machines with more than 64 cores, at least not in the
++        * current release.
++        * ENEA_end
+         */
+        sprintf(last_cpu, "%d", cpumask_last(cpu_present_mask));
+        cpulist_replace_token(cpulist, buf, "last", last_cpu);
++       cpulist_replace_token(cpulist, buf, "63", last_cpu);
+ 
+        r = bitmap_parselist(cpulist, cpumask_bits(dstp), nr_cpumask_bits);
+ 
+-- 
+2.17.1
+
diff --git a/features/cpulist_abbrev/cpulist_abbrev_enea.scc b/features/cpulist_abbrev/cpulist_abbrev_enea.scc
new file mode 100644
index 0000000..5914ce9
--- /dev/null
+++ b/features/cpulist_abbrev/cpulist_abbrev_enea.scc
@@ -0,0 +1 @@
+patch 0001-cpumask-Add-63-alias-for-last-in-cpu-list.patch