[The context here is FreeBSD head -r341836 based and ports head -r488859 based.]
Note: I assume that "struct target_semd_ds" is meant to match the memory layout
of the target's native "struct semid_ds". Otherwise the reported differences
below could be irrelevant.
For armv7 (and likely armv6) the following code:
printf("sizeof(struct semid_ds) = %lu\n", (unsigned long) sizeof(struct
semid_ds));
printf("sem_perm %lu\n", (unsigned long) offsetof(struct semid_ds,
sem_perm));
printf("__sem_base %lu\n", (unsigned long) offsetof(struct semid_ds,
__sem_base));
printf("sem_nsems %lu\n", (unsigned long) offsetof(struct semid_ds,
sem_nsems));
printf("sem_otime %lu\n", (unsigned long) offsetof(struct semid_ds,
sem_otime));
printf("sem_ctime %lu\n", (unsigned long) offsetof(struct semid_ds,
sem_ctime));
produces:
sizeof(struct semid_ds) = 48
sem_perm 0
__sem_base 24
sem_nsems 28
sem_otime 32
sem_ctime 40
However gdb reports for qemu-arm-static (on amd64):
(gdb) p/d sizeof(struct target_semid_ds)
$25 = 40
(gdb) p/d &((struct target_semid_ds *)0)->sem_perm
$26 = 0
(gdb) p/d &((struct target_semid_ds *)0)->sem_base
$27 = 24
(gdb) p/d &((struct target_semid_ds *)0)->sem_nsems
$28 = 28
(gdb) p/d &((struct target_semid_ds *)0)->sem_otime
$29 = 32
(gdb) p/d &((struct target_semid_ds *)0)->sem_ctime
$30 = 36
so after sem_otime the offsets are different.
/usr/include/sys/sem.h has:
struct semid_ds {
struct ipc_perm sem_perm; /* operation permission struct */
struct sem *__sem_base; /* pointer to first semaphore in set */
unsigned short sem_nsems; /* number of sems in set */
time_t sem_otime; /* last operation time */
time_t sem_ctime; /* last change time */
/* Times measured in secs since */
/* 00:00:00 UTC, Jan. 1, 1970, without
leap seconds */
};
/wrkdirs/usr/ports/emulators/qemu-user-static/work/qemu-bsd-user-4ef7d07/bsd-user/syscall_defs.h
has:
struct target_semid_ds {
struct target_ipc_perm sem_perm; /* operation permission struct */
abi_ulong sem_base; /* pointer to first semaphore in set */
uint16_t sem_nsems; /* number of sems in set */
abi_ulong sem_otime; /* last operation time */
abi_ulong sem_ctime; /* times measured in secs */
};
abi_ulong's for sem_otime, and sem_otime are the wrong
size for armv7: arm uses 64-bit time_t. As of 12+ only i386
uses 32-bit time_t if I understand right. In 11.x 32-bit powerpc
also uses 32-bit time_t.
===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)
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