Messages in this thread | | | Date | Wed, 6 Nov 2002 09:07:34 -0500 (EST) | From | "Richard B. Johnson" <> | Subject | Re: A hole in kernel space! |
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On Wed, 6 Nov 2002, Marc A. Volovic wrote:
> Quoth Pannaga Bhushan: > > > Hi all, > > I am looking for a setup where I need to have a certain amount > > of data always available to the kernel. The size of data I am looking at > > is abt > > 40MB(preferably, but I will settle for 20MB too) . So the normal kmalloc > > I wrote a driver which steals a certain amount of memory from the kernel > and makes it available to userspace (somewhat like the rd driver). > If you want - I can send it to you. > > It exports a small device hierarchy which can be read, written and > mmap'ed. The memory is contiguous. Not VERY elegant, but works quite > well. > > The driver steals a certain amount of memory from the kernel at boot > time, a-la the mem= parameter. I have used "holes" of up to 1GB in size. > > > Marc
You know, I hope, that you can kmalloc(GFP_KERNEL) something in init_module() and it will always be resident in the kernel until you kfree() it in cleanup_module(). You do not have to allocate/deallocate every time your module does something.
If you need a physical location, mmap() and ioremap() take care of that. With these capabilities, I don't think you need "holes" even if you are trying to map-out bad RAM. I think you need to re-think your requirements.
Cheers, Dick Johnson Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips). Bush : The Fourth Reich of America
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