library: expand fields yet maintain ABI, <MEMINFO> api

With the 4.8 kernel, 2 new fields will be added to the
meminfo pseudo file. This commit, soon to be replaced,
is intended as an example of how such changes might be
incorporated plus still maintain binary compatibility.

This actually goes further than is strictly necessary,
by retaining meminfo_item ordering for 'set' functions
and the creation of hash table entries. However, there
is only 1 true requirement, that of Item_table entries
which must always agree exactly with item enumerators.
All of the other changes could be done alphabetically.

Ok, so what happens when an old program encounters the
new expanded meminfo items? Well, if it was thoroughly
tested against an old library, it won't even see those
new fields. On the other hand, if it somehow exceeds a
previous MEMINFO_logical_end, then it will just get an
extra result structure or two, with no real harm done.

[ this patch is being replace by the very next patch ]
[ so that our iniitial newlib release can maintain a ]
[ strict alphabetic ordering in all areas initially! ]

Signed-off-by: Jim Warner <james.warner@comcast.net>

diff --git a/proc/meminfo.c b/proc/meminfo.c
index ee8ecbe34f77873b210ff8435f360c9004438420..2bf31a0bf2df9b7b74743cf2ba4c1ca35474b94e 100644 (file)
--- a/proc/meminfo.c
+++ b/proc/meminfo.c
@@ -91,6 +91,10 @@ struct meminfo_data {
     unsigned long derived_mem_lo_used;
     unsigned long derived_mem_used;
     unsigned long derived_swap_used;
+
+    // new with kernel 4.8
+    unsigned long ShmemHugePages;
+    unsigned long ShmemPmdMapped;
 };
 
 struct mem_hist {
@@ -225,6 +229,12 @@ MEM_set(SWAP_FREE,              ul_int,  SwapFree)
 MEM_set(SWAP_TOTAL,             ul_int,  SwapTotal)
 MEM_set(SWAP_USED,              ul_int,  derived_swap_used)
 
+    // new with kernel 4.8
+MEM_set(MEM_SHMEM_HUGE,         ul_int,  ShmemHugePages)
+MEM_set(MEM_SHMEM_HUGE_MAP,     ul_int,  ShmemPmdMapped)
+HST_set(DELTA_SHMEM_HUGE,        s_int,  ShmemHugePages)
+HST_set(DELTA_SHMEM_HUGE_MAP,    s_int,  ShmemPmdMapped)
+
 #undef setDECL
 #undef MEM_set
 #undef HST_set
@@ -344,13 +354,19 @@ static struct {
   { RS(SWAP_TOTAL),            TS(ul_int) },
   { RS(SWAP_USED),             TS(ul_int) },
 
+    // new with kernel 4.8
+  { RS(MEM_SHMEM_HUGE),        TS(ul_int) },
+  { RS(MEM_SHMEM_HUGE_MAP),    TS(ul_int) },
+  { RS(DELTA_SHMEM_HUGE),      TS(s_int)  },
+  { RS(DELTA_SHMEM_HUGE_MAP),  TS(s_int)  },
+
  // dummy entry corresponding to MEMINFO_logical_end ...
   { NULL,                      NULL       }
 };
 
     /* please note,
      * this enum MUST be 1 greater than the highest value of any enum */
-enum meminfo_item MEMINFO_logical_end = MEMINFO_SWAP_USED + 1;
+enum meminfo_item MEMINFO_logical_end = MEMINFO_DELTA_SHMEM_HUGE_MAP + 1;
 
 #undef setNAME
 #undef RS
@@ -527,6 +543,10 @@ static int make_hash_failed (
     htVAL(Writeback)
     htVAL(WritebackTmp)
 
+    // new with kernel 4.8
+    htVAL(ShmemHugePages)
+    htVAL(ShmemPmdMapped)
+
     return 0;
  #undef htVAL
  #undef htXTRA

diff --git a/proc/meminfo.h b/proc/meminfo.h
index bd214d48da304b5d109c8caec30aed59447c6ebe..3b7620a59128f142613de6da77ada876d01ea830 100644 (file)
--- a/proc/meminfo.h
+++ b/proc/meminfo.h
@@ -120,7 +120,14 @@ enum meminfo_item {
     MEMINFO_SWAP_CACHED,           //  ul_int
     MEMINFO_SWAP_FREE,             //  ul_int
     MEMINFO_SWAP_TOTAL,            //  ul_int
-    MEMINFO_SWAP_USED              //  ul_int
+    MEMINFO_SWAP_USED,             //  ul_int
+
+    // new with kernel 4.8
+    MEMINFO_MEM_SHMEM_HUGE,        //  ul_int
+    MEMINFO_MEM_SHMEM_HUGE_MAP,    //  ul_int
+
+    MEMINFO_DELTA_SHMEM_HUGE,      //   s_int
+    MEMINFO_DELTA_SHMEM_HUGE_MAP,  //   s_int
 };