Payload limitation on kern_ctl_reg
Payload limitation on kern_ctl_reg
- Subject: Payload limitation on kern_ctl_reg
- From: Prokash Sinha <email@hidden>
- Date: Wed, 15 Apr 2015 15:01:22 -0700
Folks,
Is there a a limit to the data payload for this type control/socket interface ?
The kext does provide the ctl, app connects to the ctl using socket interface from the user space.
Kext is the data provider. I’ve a choice of tacking a pointer inside the event structure, but that is a kernel vm address without proper mapping. So I can stick data in a way, that the event structure will have it….
So when the event is posted using lev_msg_post(&msg), where msg is struct lev_msg, the msg.dv[0].data_length is where the data length is filled out, and msg.dv[0].data is the address of data.
It seems like the maximum amount of data that can be placed here is 160 bytes or little more.
Is there any restriction for this?
My requirement is between 2K to 3K max, less than a page, so may be I should be able to shovel a page at the most in any event.
Otherwise I will have resort to kernel to use memory mapping.
Any suggestion ?
Thanks,
Prokash
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