Messages in this thread | | | Subject | Re: [patch] x86: allow ZONE_DMA to be configurable | From | "H. Peter Anvin" <> | Date | Wed, 13 Oct 2010 18:21:48 -0700 |
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And the value of those additional options is what? I'd consider adding this to the sewer pit called CONFIG_EMBEDDED (with a BUG_ON, not a warning... sheesh) but only if there is any demonstrable value other than a trivial amount of code (kilobytes?) in exchange for a bunch of crap #ifdef.
"David Rientjes" <rientjes@google.com> wrote:
>On Wed, 13 Oct 2010, H. Peter Anvin wrote: > >> > You can already set the lowmem_reserve_ratio via >> > /proc/sys/vm/lowmem_reserve_ratio. >> >> And why is it then so hard to put in a single line in /etc/sysctl.conf >> for you? >> > >Because disabling CONFIG_ZONE_DMA allows for additional extensions: >disabling CONFIG_GENERIC_ISA_DMA and CONFIG_ISA_DMA_API. We've also run >for a couple years without those. > >> > We've run without ZONE_DMA for a couple years because we don't have such >> > hardware limitations and would appreciate the ability to disable it with a >> > config option rather than hacking the kernel to get it to compile. I'm >> > sure Casey would as well as you can see in the thread "A question about >> > ZONE_DMA". >> > >> > I don't see the harm in being able to conveniently disable the zone if you >> > know what you're doing. >> >> There are going to be a lot of very strange bug reports as a result. >> > >We have config options all over the kernel that change the behavior of >syscalls without worrying about bug reports popping up from users who >knowingly have disabled the option, I don't see this as being any >different. If you're concerned about, we could add a > >#ifndef CONFIG_ZONE_DMA > WARN_ON_ONCE(gfp_mask & __GFP_DMA); >#endif > >in the page allocator.
-- Sent from my mobile phone. Please pardon any lack of formatting.
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