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SubjectRe: Reserving a (large) memory block
On Thu, 31 Aug 2000 17:12:03 +0100 (BST) 
Alan Cox <> wrote:

>> Now the device behaves just like memory to the BIOS during POST
>> etc, and is in fact, exactly memory if no device drivers are
>> loaded. If a device driver is loaded and it detects one or more
>> of these devices then they and their memory ranges become
>> obviously special. Now, we can detect the devices and where
>> their address ranges are via the SMBUS and some careful probing
>> so we know what we are trying to grab. The problem is just
>> telling the rest of the kernel that in a clean VM&heap-happy
>> manner.

> Basically your base driver will have to do it at boot up
> time. Once that memory is allocated to someone you may not be able
> to move the memory and borrow the pages.

Aye, that's what we're doing ATM. We find the board and its size,
and then go and edit mem_map and mark it reserved and uncacheable.
It doesn't seem the most graceful approach and I was hoping for
something cleaner (tho that looks like 2.4 per Ingo's comments which
I still have to look into).

> You don't neccessarily need the whole driver in the main kernel
> but you will need to grab the devices, reserve the memory pages in
> question and mark them as reserved before Linux gets going
> properly. Your actual users of these pages can then be dynamically
> loaded.

Yeah, that's what I'm looking at right now: how early I have to get
in to be safe.

J C Lawrence Home:
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