ramips: Fix early memory calculation for certain MIPS platforms

Kernel upstream commit 67a3ba25aa95 ("MIPS: Fix incorrect mem=X@Y handling") introduced a new issue for rt288x where "PHYS_OFFSET" is 0x0 but the calculated "ramstart" is not. As the prerequisite of custom memory map has been removed, this results in the full memory range of 0x0 - 0x8000000 to be marked as reserved
for this platform.

This patch adds the originally intended prerequisite again.

Signed-off-by: Tobias Wolf <dev-NTEO@vplace.de>

diff --git a/target/linux/ramips/patches-4.14/0003-MIPS-Fix-memory-reservation-in-bootmem_init-for-cert.patch b/target/linux/ramips/patches-4.14/0003-MIPS-Fix-memory-reservation-in-bootmem_init-for-cert.patch
new file mode 100644 (file)
index 0000000..d47f27e
--- /dev/null
+++ b/target/linux/ramips/patches-4.14/0003-MIPS-Fix-memory-reservation-in-bootmem_init-for-cert.patch
@@ -0,0 +1,45 @@
+From: Tobias Wolf <dev-NTEO@vplace.de>
+Subject: [v2] MIPS: Fix memory reservation in bootmem_init for certain non-usermem setups
+
+Commit 67a3ba25aa95 ("MIPS: Fix incorrect mem=X@Y handling") introduced a new
+issue for rt288x where "PHYS_OFFSET" is 0x0 but the calculated "ramstart" is
+not. As the prerequisite of custom memory map has been removed, this results
+in the full memory range of 0x0 - 0x8000000 to be marked as reserved for this
+platform.
+
+v2: Correctly compare that usermem is not null.
+
+This patch adds the originally intended prerequisite again.
+
+Signed-off-by: Tobias Wolf <dev-NTEO@vplace.de>
+---
+
+--- a/arch/mips/kernel/setup.c        2018-08-18 19:07:07.142066706 +0200
++++ b/arch/mips/kernel/setup.c        2018-08-18 19:10:17.827918423 +0200
+@@ -369,6 +369,8 @@ static unsigned long __init bootmap_byte
+       return ALIGN(bytes, sizeof(long));
+ }
+ 
++static int usermem __initdata;
++
+ static void __init bootmem_init(void)
+ {
+       unsigned long reserved_end;
+@@ -442,7 +444,7 @@ static void __init bootmem_init(void)
+       /*
+        * Reserve any memory between the start of RAM and PHYS_OFFSET
+        */
+-      if (ramstart > PHYS_OFFSET)
++      if (usermem && ramstart > PHYS_OFFSET)
+               add_memory_region(PHYS_OFFSET, ramstart - PHYS_OFFSET,
+                                 BOOT_MEM_RESERVED);
+ 
+@@ -652,8 +654,6 @@ static void __init bootmem_init(void)
+  * initialization hook for anything else was introduced.
+  */
+ 
+-static int usermem __initdata;
+-
+ static int __init early_parse_mem(char *p)
+ {
+       phys_addr_t start, size;