[U-Boot] [PATCH] get_ram_size: memory content of base address was not restored
From: Po-Yu Chuang ratbert@faraday-tech.com
Signed-off-by: Po-Yu Chuang ratbert@faraday-tech.com --- common/memsize.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/common/memsize.c b/common/memsize.c index 6c275c9..99469ab 100644 --- a/common/memsize.c +++ b/common/memsize.c @@ -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
Dear ratbert.chuang@gmail.com,
In message 1274771093-29677-1-git-send-email-ratbert.chuang@gmail.com you wrote:
From: Po-Yu Chuang ratbert@faraday-tech.com
Signed-off-by: Po-Yu Chuang ratbert@faraday-tech.com
common/memsize.c | 1 + 1 files changed, 1 insertions(+), 0 deletions(-)
diff --git a/common/memsize.c b/common/memsize.c index 6c275c9..99469ab 100644 --- a/common/memsize.c +++ b/common/memsize.c @@ -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
Dear Wolfgang,
2010/8/8 Wolfgang Denk wd@denx.de:
Dear ratbert.chuang@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
participants (3)
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Po-Yu Chuang -
ratbert.chuang＠gmail.com
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Wolfgang Denk