Re: Writing from the kernel
Re: Writing from the kernel
- Subject: Re: Writing from the kernel
- From: Terry Lambert <email@hidden>
- Date: Tue, 20 Nov 2007 14:12:01 -0800
Internal documentation in source files is pretty significantly
improved in Leopard. It's not everywhere, but we had to do this for
errno origin and value tracking for the UNIX conformance work. Mostly
this is under xnu/bsd/, but that's where you look to be looking anyway.
I'd definitely agree with Quinn that if this were anything but a
research project... well.
-- Terry
On Nov 20, 2007, at 7:54 AM, Kynan Shook <email@hidden> wrote:
Thanks for the gun, I promise I won't shoot myself in the foot. ;-)
Now, is there any documentation on these interfaces? A google on
vnode_open returns very few results...
Kynan
On Nov 20, 2007, at 5:05 AM, Quinn wrote:
In that case I would just write it to a file (-:
It's not that you /can't/ read or write files from the kernel, it's
that doing this exposes you to all sorts of crazy deadlock
situations. In this case, you're sitting at the block driver level
and you end up calling all the way back up to the VFS level. It's
very easy to deadlock due to reentrancy. It's also easy to
deadlock due to lack of resources.
OTOH, for a research project you should be able to make it work.
You can get the vnode for a path using vnode_lookup. You can open
it using vnode_open. And you can write to it using VNOP_WRITE.
You don't even have to take a dependency on the kernel; these are
all KPIs.
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