Re: Why don't we make mmap MAP_SHARED with /dev/zero possible?

Ingo Molnar
1999-11-03T21:41:40Z

On Wed, 3 Nov 1999, Benjamin C.R. LaHaise wrote:

> > it's now an unconditional __GFP_HIGHMEM in my tree. HIGHMEM gfp()
> > allocation automatically falls back to allocate in lowmem, if highmem
> > lists are empty.
>
> I'd like to look through the patches to see how you're doing things before
> making any comments. Specifically, I want to look at the buffer head

(soon, probably tomorrow)

> address thing that was mentioned -- given that the devices that support
> addressing memory above 4G will expect a 64 bit address, I don't think the
> shift is the right way to go.

i introduced bh->b_page _specifically_ to support 64-bit addresses. Below
<4GB RAM DMA32 can be supported with no IO-layer changes. Right now it
supports up to 2TB DMA64 target space (on 32-bit boxes), which is more
than enough.

-- mingo