Hello Joel,
I would provide a super set of the FreeBSD and Linux APIs for RTEMS and use a
clean implementation. In case of conflicts I would use the Linux API. Its
just managing bits.
On 2013-10-11 23:06, Joel Sherrill wrote:
Hi
We are finishing up a proposal for pthread affinity APIs. We
think we should follow the Linux API but have our own
implementation. I am trying to use the FreeBSD cpu set code
with minimal ifdefs, but there are differences which are
adding up to the point where I have a problem. Do I put in
lots of ifdef's? Or just create our own version using
the BSD version as inspiration and code fragements?
The first difference is Linux uses cpu_set_t while
FreeBSD uses cpuset_t. This can be accounted for with
a typedef. A global search and replace or using ifdefs
will result in a file with lots of changes. Assume a
typedef is OK since it minimizes impact of that.
Then you have supporting macros. The following summarizes
the similarities and differences.
These macros appear to be the same on Linux and FreeBSD.
void CPU_ZERO(cpu_set_t *set);
void CPU_SET(int cpu, cpu_set_t *set);
void CPU_CLR(int cpu, cpu_set_t *set);
int CPU_ISSET(int cpu, cpu_set_t *set);
For comparing sets, Linux has CPU_EQUAL while BSD has CPU_CMP.
The signature is the same so a renaming macro would address this.
int CPU_EQUAL(cpu_set_t *set1, cpu_set_t *set2);
FreeBSD has these extra:
void CPU_FILL(cpu_set_t *set)
bool CPU_EMPTY(cpu_set_t *set) /* is empty? */
bool CPU_SUBSET(cpu_set_t *p,cpu_set_t *c) /* is c a subset of p? */
bool CPU_OVERLAP(cpu_set_t *p,cpu_set_t *c) /* do c and p overlap? */
And these differ between FreeBSD and Linux. The Linux API has three
parameters and is performs bitwise operations on the two sources
and puts the result in destination. FreeBSD has an "|=" or "&="
and takes destination and the set to operate with. This is the
Linux API. Just drop a parameter to get FreeBSD but that makes
them incompatible.
void CPU_AND(cpu_set_t *destset,
cpu_set_t *srcset1, cpu_set_t *srcset2);
void CPU_OR(cpu_set_t *destset,
cpu_set_t *srcset1, cpu_set_t *srcset2);
void CPU_XOR(cpu_set_t *destset,
cpu_set_t *srcset1, cpu_set_t *srcset2);
FreeBSD also has NAND.
Comments, suggestions, thoughts welcomed.
--
Sebastian Huber, embedded brains GmbH
Address : Dornierstr. 4, D-82178 Puchheim, Germany
Phone : +49 89 189 47 41-16
Fax : +49 89 189 47 41-09
E-Mail : sebastian.hu...@embedded-brains.de
PGP : Public key available on request.
Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
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