[Patch, avr] Place progmem.data from avr-libc above other progmem

[Senthil Kumar Selvaraj]

Hi,

  avr-libc's vfprint handling uses a lookup table located in flash
  if float format specifiers are involved. If user code also has
  lots of flash data (in section .progmem.data), then
  avr-libc's progmem data gets pushed beyond the 64 K word limit. The
  avr-libc code doesn't expect this to happen and vfprintf stops working correctly.

  User code can easily use the  memx address space modifier to
  seamlessly access flash data above 64K. The avr-libc project doesn't
  use address space modifiers yet, and the lookup logic itself is
  written in assembly, so I guess it is not going to gain this ability
  soon.

  Given these constraints, this patch places progmem.data coming from
  avr-libc's routines above other progmem.data, increasing the
  likelyhood that it gets placed below the 64 K limit. If this is ok,
  could someone commit please? I don't have commit access.

Regards
Senthil

2016-05-15  Senthil Kumar Selvaraj  <senthil_kumar.selvaraj@atmel.com>

	* scripttempl/avr.sc (text): Place .progmem.data
  from avr-libc above .progmem*.
  * scripttempl/avrtiny.sc (text): Likewise.


diff --git ld/scripttempl/avr.sc ld/scripttempl/avr.sc
index c26f4ea..80064cb 100644
--- ld/scripttempl/avr.sc
+++ ld/scripttempl/avr.sc
@@ -113,6 +113,10 @@ SECTIONS
     ${RELOCATING+ *(.trampolines*)}
     ${CONSTRUCTING+ __trampolines_end = . ; }
 
+    /* avr-libc expects these data to reside in lower 64K. */
+    *libprintf_flt.a:*(.progmem.data)
+    *libc.a:*(.progmem.data)
+
     ${RELOCATING+ *(.progmem*)}
     
     ${RELOCATING+. = ALIGN(2);}
diff --git ld/scripttempl/avrtiny.sc ld/scripttempl/avrtiny.sc
index 0441dcb..234c7c7 100644
--- ld/scripttempl/avrtiny.sc
+++ ld/scripttempl/avrtiny.sc
@@ -113,6 +113,9 @@ SECTIONS
     ${RELOCATING+ *(.trampolines*)}
     ${CONSTRUCTING+ __trampolines_end = . ; }
 
+    /* avr-libc expects these data to reside in lower 64K. */
+    *libprintf_flt.a:*(.progmem.data)
+    *libc.a:*(.progmem.data)
     ${RELOCATING+ *(.progmem*)}
 
     ${RELOCATING+. = ALIGN(2);}