Hellow!
Frederick M. Proctor's example program("shmex") to test shared memory
does not work.
It can not communicate with each other using the shared memory. When a
process read data in the shared memory, data is correctly read, if data
is wriiten by that process. If data is written other process, then data
is alway zero.
Shared Memory HOWTO is different from Frederick M. Proctor's example
program on the mmap flags.
mmap flag is set to MAP_PRIVATE in Shared Memory HOWTO document , but
set to MAP_SHARED in Frederick M. Proctor's example program.
in Shared Memory HOWTO document:
user_ptr = (char * ) mmap ( 0, 0x100000, PROT_READ,
MAP_FILE |MAP_PRIVATE, fdm,
ADDRESS);
in Frederick M. Proctor's example program
ptr = (MY_STRUCT *) mmap(0, sizeof(MY_STRUCT),
PROT_READ | PROT_WRITE,
MAP_FILE | MAP_SHARED,
fd, BASE_ADDRESS);
My PC configuration is flowed
CPU : petium 133 MHz
main memory : 32M
Kernel version : 2.0.35
lilo version : 20
Linux version : RedHat 4.0
RTLinux version : 0.9
my lilo.conf is
boot=/dev/hda
map=/boot/map
install=/boot/boot.b
prompt
timeout=50
image=/boot/zImage
label=RT_LINUX_0.9
root=/dev/hda1
read-only
append = "mem=31m"
I need your help.
Thank you.
Taeam Choi
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