At 10:36 PM 6/7/99 +0100, Alan Cox wrote:
>> >So write a library that wraps it as you want it. Or just go and look on
>> >freshmeat for a couple that exist.
>>
>> i am describing a bug in linux and you write now i must fix it?
>
>Linux != Linux Kernel. The Linux kernel implements the interfaces as defined
>by the Unix standards. The interface to a user application is a library
>problem. If you want a cute interface you can write a library for it or
>use one of the exiting libraries
So you are saying this is a gcc problem?
I don't think so.
checkout mmap for example. in UNIX you can do an anonymous and
shared map. This is what i do in NT. In Linux this isn't implement
yet in the kernel.
You can't create in the linux kernel a shared memory region that's
bigger than 32 megabytes. You CAN allocate more than
32 mb if you do what i described in previous email, but then
you allocate it IPC_PRIVATE.
It's really a kernel problem and not a library problem.
The KERNEL doesn't allow
a) anonymous shared file mapping (which is the easiest way for
a programmer to use shared memory as that has obviously
less bad habits than shmget/shmat). So when i use mmap() i don't
want to PHYSICALLY create half a gigabyte file, and then need
10 minutes to swap it in (even though harddisk is 80mb/s),
before i can use the 0.45 mb memory for my program. I want
of course an option (in NT that's filedescriptor== -1)
to use an anonymous file.
b) with shmget
standard only 32 mb maximal allowed to allocate from kernel.
To get 450 mb is a real problem.
If that aren't kernel problems i'm not sure from what planet you are.
>> >You can attach an shm object and then delete it. It goes away on the last
>> >user death
>>
>> it doesn't.
>
>Then you have another kernel bug or your request to delete it after attach
>failed and you didnt check the errno. What kernel are you using. If its 2.0
>and threaded then it could well be a real problem
all new versions. Ask Robert Hyatt for what version kernel is
2.2.9 or something i guess.
>> >Shared memory can be swapped. If linux is crashing then you've found a bug
>> >whether it gets swapped or not.
>>
>> quite easy bug to reproduce at your system. I've given all the
>> code needed.
>
>Can you mail me the actual code and I'll try it. Include some info on your
>machine configuration and kernel rev with it.
not my own machine. quad pentium pro 200. at that system
linux 2.2.5 is installed. The quad xeon has the same problem.
>Alan
>
>
>
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