Messages in this thread | | | Subject | Re: Why no bigphysarea in mainline? | From | Dave Hansen <> | Date | Thu, 17 Mar 2005 06:35:32 -0800 |
| |
On Thu, 2005-03-17 at 20:57 +1100, Michael Ellerman wrote: > I realise bigphysarea is a bit of a hack, but it's no where near as > big a hack as using mem=X to limit the kernel's memory and then using > the rest of memory for your device driver.
Well, the fact that you can get away with that is a coincidence. What if you have 4GB of RAM on an x86 machine, you do mem=3G, and you start using that top GB of memory for your driver? You eventually write into the PCI config space. Ooops. You get strange errors that way.
Doing mem= for drivers isn't just a hack, it's *WRONG*. It's a ticking time bomb that magically happens to work on some systems. It will not work consistently on a discontiguous memory system, or a memory hotplug system.
> If no one has any fundamental objections I think it'd be good to get > this merged into mainline so people start using it rather than mem=X > hacks. To that end please let me know what you think is wrong with > the patch as it stands (below).
Could you give some examples of drivers which are in the kernel that could benefit from this patch? We don't tend to put things like this in, unless they have actual users. We don't tend to change code for out-of-tree users, either.
-- Dave
- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |