workspace: update linux to 6.12.15

Switch to the current 6.12 LTS branch and rebase the patches.
Also switch to using savedefconfig for config instead of just including
the entire thing. This makes it much more readable as it only contains
settings we've touched.

Change-Id: I2b15944f0083399290a2539c42e37205e839bf36
Reviewed-on: https://review.monogon.dev/c/monogon/+/3908
Tested-by: Jenkins CI
Reviewed-by: Tim Windelschmidt <tim@monogon.tech>
diff --git a/third_party/linux/patches/enable-pmsg.patch b/third_party/linux/patches/enable-pmsg.patch
index 8886d94..11b67cb 100644
--- a/third_party/linux/patches/enable-pmsg.patch
+++ b/third_party/linux/patches/enable-pmsg.patch
@@ -1,10 +1,20 @@
-This enables pstore for userspace messages for the ACPI ERST as well as the
-EFI variable pstore backend, both of which are expected to be used frequently
-with Metropolis. We need that to reliably store panics of core processes
-regardless of the system state. This is not enabled upstream, either because
-pmsg was a later addition to pstore or for concerns of accidentally running
-out of pstore space. We work around the limited space issue by always clearing
-pstore after every boot, so this poses little extra risk to us.
+From 9558d3ae7a94a56e64e1ba00469b21c721323d0c Mon Sep 17 00:00:00 2001
+From: Lorenz Brun <lorenz@monogon.tech>
+Date: Mon, 29 Jan 2024 22:17:13 +0100
+Subject: [PATCH] drivers: pstore: enable pmsg for ERST and EFI backends
+
+This enables pstore for userspace messages for the ACPI ERST as well as
+the EFI variable pstore backend, both of which are expected to be used
+frequently with Metropolis. We need that to reliably store panics of
+core processes regardless of the system state. This is not enabled
+upstream, either because pmsg was a later addition to pstore or for
+concerns of accidentally running out of pstore space. We work around
+the limited space issue by always clearing pstore after every boot, so
+this poses little extra risk to us.
+---
+ drivers/acpi/apei/erst.c          | 2 +-
+ drivers/firmware/efi/efi-pstore.c | 2 +-
+ 2 files changed, 2 insertions(+), 2 deletions(-)
 
 diff --git a/drivers/acpi/apei/erst.c b/drivers/acpi/apei/erst.c
 index bf65e3461531..fe2c331b4b99 100644
@@ -20,10 +30,10 @@
  	.close		= erst_close_pstore,
  	.read		= erst_reader,
 diff --git a/drivers/firmware/efi/efi-pstore.c b/drivers/firmware/efi/efi-pstore.c
-index e7b9ec6f8a86..7570499b46e0 100644
+index 552c78f5f059..9e5651fd1439 100644
 --- a/drivers/firmware/efi/efi-pstore.c
 +++ b/drivers/firmware/efi/efi-pstore.c
-@@ -210,7 +210,7 @@ static int efi_pstore_erase(struct pstore_record *record)
+@@ -245,7 +245,7 @@ static int efi_pstore_erase(struct pstore_record *record)
  static struct pstore_info efi_pstore_info = {
  	.owner		= THIS_MODULE,
  	.name		= KBUILD_MODNAME,
@@ -32,3 +42,6 @@
  	.open		= efi_pstore_open,
  	.close		= efi_pstore_close,
  	.read		= efi_pstore_read,
+-- 
+2.47.2
+