[U-Boot] [PATCH v3 4/6] dlmalloc: add option for skip memset in malloc init

[Przemyslaw Marczak]

This commit introduces new config: CONFIG_SYS_MALLOC_INIT_SKIP_ZEROING.

Before this change, the all amount of memory reserved for the malloc,
was set to zero in mem_malloc_init(). When the malloc reserved memory
exceeds few MiB, then the boot process can slow down.

So enabling this config, is an option to reduce the boot time.

This option can be enabled by Kconfig.

Note:
After enable this option, only calloc() will return the pointer to zeroed
memory area. Previously, without this option, the memory pointed to untouched
malloc memory region, was filled with zeros. So it means, that code with
malloc() calls should be reexamined.

Signed-off-by: Przemyslaw Marczak <p.marczak at samsung.com>
Reviewed-by: Simon Glass <sjg at chromium.org>

---
Changes v3:
- squash the commit with the Kconfig option
---
 Kconfig           | 26 +++++++++++++++++++-------
 common/dlmalloc.c | 10 +++++++---
 2 files changed, 26 insertions(+), 10 deletions(-)

diff --git a/Kconfig b/Kconfig
index 75bab7f..87d4daf 100644
--- a/Kconfig
+++ b/Kconfig
@@ -76,13 +76,25 @@ config SYS_MALLOC_F_LEN
 	  initial serial device and any others that are needed.
 
 menuconfig EXPERT
-        bool "Configure standard U-Boot features (expert users)"
-        help
-          This option allows certain base U-Boot options and settings
-          to be disabled or tweaked. This is for specialized
-          environments which can tolerate a "non-standard" U-Boot.
-          Only use this if you really know what you are doing.
-
+	bool "Configure standard U-Boot features (expert users)"
+	help
+	  This option allows certain base U-Boot options and settings
+	  to be disabled or tweaked. This is for specialized
+	  environments which can tolerate a "non-standard" U-Boot.
+	  Only use this if you really know what you are doing.
+
+if EXPERT
+	config SYS_MALLOC_INIT_SKIP_ZEROING
+	bool "Skip memset at malloc init (reduce boot time)"
+	help
+	  This avoids zeroing memory reserved for malloc at malloc init.
+	  Significant boot time reduction is visible for configs in which
+	  CONFIG_SYS_MALLOC_LEN value, has more than few MiB.
+	  Useful for bzip2, bmp logo.
+	  Warning:
+	  When enabling this, please check if malloc calls, maybe
+	  should be replaced by calloc - if expects zeroed memory.
+endif
 endmenu		# General setup
 
 menu "Boot images"
diff --git a/common/dlmalloc.c b/common/dlmalloc.c
index 6453ee9..63f68ed 100644
--- a/common/dlmalloc.c
+++ b/common/dlmalloc.c
@@ -1535,9 +1535,9 @@ void mem_malloc_init(ulong start, ulong size)
 
 	debug("using memory %#lx-%#lx for malloc()\n", mem_malloc_start,
 	      mem_malloc_end);
-
-	memset((void *)mem_malloc_start, 0, size);
-
+#ifndef CONFIG_SYS_MALLOC_INIT_SKIP_ZEROING
+	memset((void *)mem_malloc_start, 0x0, size);
+#endif
 	malloc_bin_reloc();
 }
 
@@ -2948,10 +2948,12 @@ Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size;
 
 
   /* check if expand_top called, in which case don't need to clear */
+#ifndef CONFIG_SYS_MALLOC_INIT_SKIP_ZEROING
 #if MORECORE_CLEARS
   mchunkptr oldtop = top;
   INTERNAL_SIZE_T oldtopsize = chunksize(top);
 #endif
+#endif
   Void_t* mem = mALLOc (sz);
 
   if ((long)n < 0) return NULL;
@@ -2977,6 +2979,7 @@ Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size;
 
     csz = chunksize(p);
 
+#ifndef CONFIG_SYS_MALLOC_INIT_SKIP_ZEROING
 #if MORECORE_CLEARS
     if (p == oldtop && csz > oldtopsize)
     {
@@ -2984,6 +2987,7 @@ Void_t* cALLOc(n, elem_size) size_t n; size_t elem_size;
       csz = oldtopsize;
     }
 #endif
+#endif
 
     MALLOC_ZERO(mem, csz - SIZE_SZ);
     return mem;
-- 
1.9.1