From 1083f3681841f79903c56a31504ce1a00f5e5501 Mon Sep 17 00:00:00 2001
From: Juan Yescas <jyescas@google.com>
Date: Fri, 14 Jul 2023 10:42:31 -0700
Subject: [PATCH] 16k: core: Add flag to make AOSP page size agnostic

The new boolean flag will be PRODUCT_PAGE_SIZE_AGNOSTIC.

When PRODUCT_PAGE_SIZE_AGNOSTIC is true:

- AOSP will use getpagesize() to retrieve the page size.
- The flag `TARGET_MAX_PAGE_SIZE_SUPPORTED` has to be equals to `65536`.
- AOSP will be able to use 4k/16k page size Linux kernels

When PRODUCT_PAGE_SIZE_AGNOSTIC is false:

- AOSP will only support 4k page size kernels.

Test: source build/envsetup.sh
      lunch aosp_raven_64-userdebug
      get_build_var TARGET_PAGE_SIZE_AGNOSTIC
      get_build_var PRODUCT_MAX_PAGE_SIZE_SUPPORTED
      65536

      source build/envsetup.sh
      lunch aosp_raven_64-userdebug
      build/make/core/config.mk:414: error: TARGET_MAX_PAGE_SIZE_SUPPORTED has to be 65536 to support page size agnostic.
      10:32:55 dumpvars failed with: exit status 1

Bug: 289419664
Change-Id: If8fc243a3e2cad77414a53a29805c7b6d349d4dd
---
 core/config.mk       | 14 ++++++++++++++
 core/product.mk      |  4 ++++
 core/soong_config.mk |  1 +
 3 files changed, 19 insertions(+)

diff --git a/core/config.mk b/core/config.mk
index 55ff6baaa7..920e4575b5 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -425,6 +425,7 @@ ifdef PRODUCT_SHIPPING_API_LEVEL
 endif
 
 # Set TARGET_MAX_PAGE_SIZE_SUPPORTED.
+# TARGET_MAX_PAGE_SIZE_SUPPORTED indicates the alignment of the ELF segments.
 ifdef PRODUCT_MAX_PAGE_SIZE_SUPPORTED
   TARGET_MAX_PAGE_SIZE_SUPPORTED := $(PRODUCT_MAX_PAGE_SIZE_SUPPORTED)
 else ifeq ($(strip $(call is-low-mem-device)),true)
@@ -440,6 +441,19 @@ else
 endif
 .KATI_READONLY := TARGET_MAX_PAGE_SIZE_SUPPORTED
 
+# Boolean variable determining if AOSP is page size agnostic. This means
+# that AOSP can use a kernel configured with 4k/16k/64k PAGE SIZES.
+TARGET_PAGE_SIZE_AGNOSTIC := false
+ifdef PRODUCT_PAGE_SIZE_AGNOSTIC
+  TARGET_PAGE_SIZE_AGNOSTIC := $(PRODUCT_PAGE_SIZE_AGNOSTIC)
+  ifeq ($(TARGET_PAGE_SIZE_AGNOSTIC),true)
+      ifneq ($(TARGET_MAX_PAGE_SIZE_SUPPORTED),65536)
+          $(error TARGET_MAX_PAGE_SIZE_SUPPORTED has to be 65536 to support page size agnostic)
+      endif
+  endif
+endif
+.KATI_READONLY := TARGET_PAGE_SIZE_AGNOSTIC
+
 # Pruned directory options used when using findleaves.py
 # See envsetup.mk for a description of SCAN_EXCLUDE_DIRS
 FIND_LEAVES_EXCLUDES := $(addprefix --prune=, $(SCAN_EXCLUDE_DIRS) .repo .git)
diff --git a/core/product.mk b/core/product.mk
index 99b3dea439..b66f1e2e69 100644
--- a/core/product.mk
+++ b/core/product.mk
@@ -33,6 +33,10 @@ _product_single_value_vars += PRODUCT_MODEL_FOR_ATTESTATION
 # 4096, 16384 and 65536.
 _product_single_value_vars += PRODUCT_MAX_PAGE_SIZE_SUPPORTED
 
+# Indicates that AOSP can use a kernel configured with 4k/16k/64k page sizes.
+# The possible values are true or false.
+_product_single_value_vars += PRODUCT_PAGE_SIZE_AGNOSTIC
+
 # The resource configuration options to use for this product.
 _product_list_vars += PRODUCT_LOCALES
 _product_list_vars += PRODUCT_AAPT_CONFIG
diff --git a/core/soong_config.mk b/core/soong_config.mk
index d8b18e731a..f150660582 100644
--- a/core/soong_config.mk
+++ b/core/soong_config.mk
@@ -150,6 +150,7 @@ $(call add_json_bool, Malloc_zero_contents,              $(call invert_bool,$(fi
 $(call add_json_bool, Malloc_pattern_fill_contents,      $(MALLOC_PATTERN_FILL_CONTENTS))
 $(call add_json_str,  Override_rs_driver,                $(OVERRIDE_RS_DRIVER))
 $(call add_json_str,  DeviceMaxPageSizeSupported,        $(TARGET_MAX_PAGE_SIZE_SUPPORTED))
+$(call add_json_bool, Device_page_size_agnostic,         $(filter true,$(TARGET_PAGE_SIZE_AGNOSTIC)))
 
 $(call add_json_bool, UncompressPrivAppDex,              $(call invert_bool,$(filter true,$(DONT_UNCOMPRESS_PRIV_APPS_DEXS))))
 $(call add_json_list, ModulesLoadedByPrivilegedModules,  $(PRODUCT_LOADED_BY_PRIVILEGED_MODULES))