[PATCH] powerpc: Unify mem= handling

We currently do mem= handling in three seperate places. And as benh pointed out
I wrote two of them. Now that we parse command line parameters earlier we can
clean this mess up.

Moving the parsing out of prom_init means the device tree might be allocated
above the memory limit. If that happens we'd have to move it. As it happens
we already have logic to do that for kdump, so just genericise it.

This also means we might have reserved regions above the memory limit, if we
do the bootmem allocator will blow up, so we have to modify
lmb_enforce_memory_limit() to truncate the reserves as well.

Tested on P5 LPAR, iSeries, F50, 44p. Tested moving device tree on P5 and
44p and F50.

Signed-off-by: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 5 insertions, 50 deletions

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 078fb5533541..a52377c68fc6 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -194,8 +194,6 @@ static int __initdata of_platform;
 
 static char __initdata prom_cmd_line[COMMAND_LINE_SIZE];
 
-static unsigned long __initdata prom_memory_limit;
-
 static unsigned long __initdata alloc_top;
 static unsigned long __initdata alloc_top_high;
 static unsigned long __initdata alloc_bottom;
@@ -594,16 +592,6 @@ static void __init early_cmdline_parse(void)
         }
 #endif
 
-        opt = strstr(RELOC(prom_cmd_line), RELOC("mem="));
-        if (opt) {
-                opt += 4;
-                RELOC(prom_memory_limit) = prom_memparse(opt, (const char **)&opt);
-#ifdef CONFIG_PPC64
-                /* Align to 16 MB == size of ppc64 large page */
-                RELOC(prom_memory_limit) = ALIGN(RELOC(prom_memory_limit), 0x1000000);
-#endif
-        }
-
 #ifdef CONFIG_KEXEC
         /*
          * crashkernel=size@addr specifies the location to reserve for
@@ -1115,29 +1103,6 @@ static void __init prom_init_mem(void)
         }
 
         /*
-         * If prom_memory_limit is set we reduce the upper limits *except* for
-         * alloc_top_high. This must be the real top of RAM so we can put
-         * TCE's up there.
-         */
-
-        RELOC(alloc_top_high) = RELOC(ram_top);
-
-        if (RELOC(prom_memory_limit)) {
-                if (RELOC(prom_memory_limit) <= RELOC(alloc_bottom)) {
-                        prom_printf("Ignoring mem=%x <= alloc_bottom.\n",
-                                RELOC(prom_memory_limit));
-                        RELOC(prom_memory_limit) = 0;
-                } else if (RELOC(prom_memory_limit) >= RELOC(ram_top)) {
-                        prom_printf("Ignoring mem=%x >= ram_top.\n",
-                                RELOC(prom_memory_limit));
-                        RELOC(prom_memory_limit) = 0;
-                } else {
-                        RELOC(ram_top) = RELOC(prom_memory_limit);
-                        RELOC(rmo_top) = min(RELOC(rmo_top), RELOC(prom_memory_limit));
-                }
-        }
-
-        /*
          * Setup our top alloc point, that is top of RMO or top of
          * segment 0 when running non-LPAR.
          * Some RS64 machines have buggy firmware where claims up at
@@ -1149,9 +1114,9 @@ static void __init prom_init_mem(void)
                 RELOC(rmo_top) = RELOC(ram_top);
         RELOC(rmo_top) = min(0x30000000ul, RELOC(rmo_top));
         RELOC(alloc_top) = RELOC(rmo_top);
+        RELOC(alloc_top_high) = RELOC(ram_top);
 
         prom_printf("memory layout at init:\n");
-        prom_printf("  memory_limit : %x (16 MB aligned)\n", RELOC(prom_memory_limit));
         prom_printf("  alloc_bottom : %x\n", RELOC(alloc_bottom));
         prom_printf("  alloc_top    : %x\n", RELOC(alloc_top));
         prom_printf("  alloc_top_hi : %x\n", RELOC(alloc_top_high));
@@ -1348,16 +1313,10 @@ static void __init prom_initialize_tce_table(void)
 
         reserve_mem(local_alloc_bottom, local_alloc_top - local_alloc_bottom);
 
-        if (RELOC(prom_memory_limit)) {
-                /*
-                 * We align the start to a 16MB boundary so we can map
-                 * the TCE area using large pages if possible.
-                 * The end should be the top of RAM so no need to align it.
-                 */
-                RELOC(prom_tce_alloc_start) = _ALIGN_DOWN(local_alloc_bottom,
-                                                          0x1000000);
-                RELOC(prom_tce_alloc_end) = local_alloc_top;
-        }
+        /* These are only really needed if there is a memory limit in
+         * effect, but we don't know so export them always. */
+        RELOC(prom_tce_alloc_start) = local_alloc_bottom;
+        RELOC(prom_tce_alloc_end) = local_alloc_top;
 
         /* Flag the first invalid entry */
         prom_debug("ending prom_initialize_tce_table\n");
@@ -2265,10 +2224,6 @@ unsigned long __init prom_init(unsigned long r3, unsigned long r4,
         /*
          * Fill in some infos for use by the kernel later on
          */
-        if (RELOC(prom_memory_limit))
-                prom_setprop(_prom->chosen, "/chosen", "linux,memory-limit",
-                             &RELOC(prom_memory_limit),
-                             sizeof(prom_memory_limit));
 #ifdef CONFIG_PPC64
         if (RELOC(ppc64_iommu_off))
                 prom_setprop(_prom->chosen, "/chosen", "linux,iommu-off",