Kernel Params for Red Hat 6.0

Question

I've been assigned to put oracle on a Dell installed RED Hat 6.0
box.
The Kernel Params are driving me nutty.
First of all, the docs are saying that SHMMAX needs to be
4294967295. I can't understand why Oracle can't just tell you
what to enter into the header straight and simple in HEX. My
hex calculator can't manipulate this magnitude. Is this
documentation even correct? It seems 2 digits too large from
everything else I'm looking at.
The rest of the kernel code is largley defined dynamically:
It looks like this.
Should I over ride all this?
#define SHMID_BITS 7
#define SHM_ID_MASK ((1<<_SHM_ID_BITS)-1)
#define SHM_IDX_SHIFT (_SHM_ID_BITS)
#define SHMIDX_BITS 15
#define SHM_IDX_MASK ((1<<_SHM_IDX_BITS)-1)
* SHMID_BITS + SHMIDX_BITS must be <= 24 on the i386 and
* SHMMAX <= (PAGE_SIZE << SHMIDX_BITS).
#define SHMMAX 0x2000000 /* max shared seg size
(bytes) */
/* Try not to change the default shipped SHMMAX - people rely on
it */
#define SHMMIN 1 /* really PAGE_SIZE */ /* min shared seg size
(bytes) */
#define SHMMNI (1<<_SHM_ID_BITS) /* max num of segs system
wide */
#define SHMALL /* max shm system wide
(pages) */ \
(1<<(_SHM_IDX_BITS+SHMID_BITS))
#define SHMLBA PAGE_SIZE /* attach addr a multiple
of this */
#define SHMSEG SHMMNI /* max shared segs per
process */
#endif /* ASMI386SHMPARAM_H */
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Answer 1

If the system cats back -1 (or -273 etc) for inputs that big, I
don't how we are going to obtain a positive outcome.
The hex is not the point. The point is that 4 gig ints echoed
into the /proc directory return negitive integers.
Ruben
Mladen Gogala (guest) wrote:
: Hexcalculator is for wimps. The real programmers use bc,
: with scale, ibase and obase options. As bc is doing
: packed decimal arithmetics, it can do calculations with
: the numbers > 4GB. Increase SHMMAX to 0x4000000, relink
: the kernel (make bzImage), restart & enjoy.
: Ruben I Safir (guest) wrote:
: : Thanks Robson
: : That translates to -1 when you cat it back. That was the
same
: : thing the kde hexcalculator did. It seems that using that
many
: : bytes triggers a signed variable.
: : Ruben
: : Robson Miranda (guest) wrote:
: : : You only need to do
: : : echo 4294967295 > /proc/sys/kernel/shmmax (I think, I'm not
: on
: : : my Linux box, so can't check now).
: : : With kernel > 2.2.x, there's no need to recompile it to
: change
: : : the maximum amount of shared memory.
: : : Robson.
: : : Ruben I Safir (guest) wrote:
: : : : I've been assigned to put oracle on a Dell installed RED
: Hat
: : : 6.0
: : : : box.
: : : : The Kernel Params are driving me nutty.
: : : : First of all, the docs are saying that SHMMAX needs to be
: : : : 4294967295. I can't understand why Oracle can't just
tell
: : you
: : : : what to enter into the header straight and simple in
HEX.
: My
: : : : hex calculator can't manipulate this magnitude. Is this
: : : : documentation even correct? It seems 2 digits too large
: from
: : : : everything else I'm looking at.
: : : : The rest of the kernel code is largley defined
dynamically:
: : : : It looks like this.
: : : : Should I over ride all this?
: : : : #define SHMID_BITS 7
: : : : #define SHM_ID_MASK ((1<<_SHM_ID_BITS)-1)
: : : : #define SHM_IDX_SHIFT (_SHM_ID_BITS)
: : : : #define SHMIDX_BITS 15
: : : : #define SHM_IDX_MASK ((1<<_SHM_IDX_BITS)-1)
: : : : * SHMID_BITS + SHMIDX_BITS must be <= 24 on the i386
: and
: : : : * SHMMAX <= (PAGE_SIZE << SHMIDX_BITS).
: : : : #define SHMMAX 0x2000000 /* max shared seg
: : size
: : : : (bytes) */
: : : : /* Try not to change the default shipped SHMMAX - people
: rely
: : : on
: : : : it */
: : : : #define SHMMIN 1 /* really PAGE_SIZE */ /* min shared seg
: : size
: : : : (bytes) */
: : : : #define SHMMNI (1<<_SHM_ID_BITS) /* max num of
segs
: : : system
: : : : wide */
: : : : #define SHMALL /* max shm system
: : wide
: : : : (pages) */ \
: : : : (1<<(_SHM_IDX_BITS+SHMID_BITS))
: : : : #define SHMLBA PAGE_SIZE /* attach addr a
: : : multiple
: : : : of this */
: : : : #define SHMSEG SHMMNI /* max shared
segs
: : per
: : : : process */
: : : : #endif /* ASMI386SHMPARAM_H */
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