get_ram_size: memory content of base address was not restored
PATCH 1/1 get_ram_size: memory content of base address was not restored
From: Po-Yu Chuang <[email protected]>
--- common/memsize.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
common/memsize.c +1 -0
@@ -74,6 +74,7 @@ long get_ram_size(volatile long *base, long maxsize)return (0 ); } + *addr = save[i];for (cnt =1 ; cnt < maxsize /sizeof (long ); cnt <<=1 ) { addr = base + cnt;/* pointer arith! */ val = *addr;
--
1.6.0.4
PATCH 1/1 get_ram_size: memory content of base address was not restored
Dear ratbert.chuang at gmail.com,
Quoted 13 lines · In message <[email protected]> you…
From: Po-Yu Chuang <[email protected]>
Signed-off-by Po-Yu Chuang <[email protected]>--- common/memsize.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)common/memsize.c +0
-0
common/memsize.c long get_ram_size(volatile long *base, long maxsize) · line 80
Quoted 7 lines
common/memsize.c +1
-0@@ -74,6 +74,7 @@ long get_ram_size(volatile long *base, long maxsize)return (0 ); } + *addr = save[i];for (cnt =1 ; cnt < maxsize /sizeof (long ); cnt <<=1 ) { addr = base + cnt;/* pointer arith! */ val = *addr;
I think this patch is wrong. The value at address (base + 0) is never saved, so there is no need to restore it (nor did we store it's value anywhere).
Best regards,
Wolfgang Denk
Signature · 5 lines
DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de The important thing about being a leader is not being right or wrong, but being *certain*. - Terry Pratchett, _Truckers_
PATCH 1/1 get_ram_size: memory content of base address was not restored
Dear Wolfgang,
2010/8/8 Wolfgang Denk <[email protected]>:
Quoted 4 lines
Dear ratbert.chuang at gmail.com,
I think this patch is wrong. The value at address (base + 0) is never saved, so there is no need to restore it (nor did we store it's value anywhere).
The value at base+0 is saved. Please see the following explanation.
long get_ram_size(volatile long *base, long maxsize)
{
volatile long *addr;
long save[32];
long cnt;
long val;
long size;
int i = 0;
for (cnt = (maxsize / sizeof (long)) >> 1; cnt > 0; cnt >>= 1) {
addr = base + cnt; /* pointer arith! */
sync ();
save[i++] = *addr;
sync ();
*addr = ~cnt;
}
addr = base;
sync ();
save[i] = *addr; <----- value of [base+0] is saved.
sync ();
*addr = 0; <----- [base+0] is modified.
sync ();
if ((val = *addr) != 0) {
/* Restore the original data before leaving the function.
*/
sync ();
*addr = save[i]; <----- value of [base+0] is restored.
for (cnt = 1; cnt < maxsize / sizeof(long); cnt <<= 1) {
addr = base + cnt;
sync ();
*addr = save[--i];
}
return (0);
}+ *addr = save[i]; <----- Therefore we should also restore [base+0] here.
for (cnt = 1; cnt < maxsize / sizeof (long); cnt <<= 1) {
addr = base + cnt; /* pointer arith! */
val = *addr;
*addr = save[--i];
if (val != ~cnt) {
size = cnt * sizeof (long);
/* Restore the original data before leaving the function.
*/
for (cnt <<= 1; cnt < maxsize / sizeof (long); cnt <<= 1) {
addr = base + cnt;
*addr = save[--i];
}
return (size);
}
}
return (maxsize);
}best regards,
Po-Yu Chuang