ARC: [plat-sim] unbork non default CONFIG_LINUX_LINK_BASE

HIGHMEM support bumped the default memory size for nsim platform to 1G.
Thus total memory ended at the very edge of start of peripherals address
space. With linux link base shifted, memory started bleeding into
peripheral space which caused early boot bad_page spew !

Fixes: 29e332261d2 ("ARC: mm: HIGHMEM: populate high memory from DT")
Reported-by: Anton Kolesov <akolesov@synopsys.com>
Signed-off-by: Vineet Gupta <vgupta@synopsys.com>

diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
index 2c2ac3f..6312f60 100644 (file)
--- a/arch/arc/Kconfig
+++ b/arch/arc/Kconfig
@@ -445,6 +445,7 @@ config LINUX_LINK_BASE
          However some customers have peripherals mapped at this addr, so
          Linux needs to be scooted a bit.
          If you don't know what the above means, leave this setting alone.
+         This needs to match memory start address specified in Device Tree
 
 config HIGHMEM
        bool "High Memory Support"

diff --git a/arch/arc/boot/dts/nsim_hs.dts b/arch/arc/boot/dts/nsim_hs.dts
index b0eb0e7..fc81879 100644 (file)
--- a/arch/arc/boot/dts/nsim_hs.dts
+++ b/arch/arc/boot/dts/nsim_hs.dts
@@ -17,7 +17,8 @@
 
        memory {
                device_type = "memory";
-               reg = <0x0 0x80000000 0x0 0x40000000    /* 1 GB low mem */
+               /* CONFIG_LINUX_LINK_BASE needs to match low mem start */
+               reg = <0x0 0x80000000 0x0 0x20000000    /* 512 MB low mem */
                       0x1 0x00000000 0x0 0x40000000>;  /* 1 GB highmem */
        };
 

diff --git a/arch/arc/mm/init.c b/arch/arc/mm/init.c
index a9305b5..7d2c4fb 100644 (file)
--- a/arch/arc/mm/init.c
+++ b/arch/arc/mm/init.c
@@ -51,7 +51,9 @@ void __init early_init_dt_add_memory_arch(u64 base, u64 size)
        int in_use = 0;
 
        if (!low_mem_sz) {
-               BUG_ON(base != low_mem_start);
+               if (base != low_mem_start)
+                       panic("CONFIG_LINUX_LINK_BASE != DT memory { }");
+
                low_mem_sz = size;
                in_use = 1;
        } else {