Re: [RFC][PATCH] Expanding the size of "start" and "end" field in "struct resource"

[ebiederm@xmission.com (Eric W. Biederman)]

Benjamin LaHaise <bcrl@kvack.org> writes:

> On Wed, Mar 15, 2006 at 02:29:32PM -0700, Eric W. Biederman wrote:
>> If the impact is very slight or unmeasurable this means the option
>> needs to fall under CONFIG_EMBEDDED, where you can change if
>> every last bit of RAM counts but otherwise you won't care.
>
> But we have a data type that is correct for this usage: dma_addr_t.

Actually now that I think back there are machines with < 4GiB of ram
with 64bit pci BAR values.  It is more common to have 32bit values BAR
values and > 4GiB of ram.

So I don't see dma_addr_t in general being the right choice.

Although I do suspect that in most cases dma_addr_t <= the
size of what is in struct resource.

Nor do I think struct resource is nearly as important when being
efficient, as dma_addr_t.  struct resource is only used during
driver setup which is a very rare event.  A few extra instructions
there likely will get lost in the noise and most of the will probably
be removed because they are in an __init section anyway.

Eric