Arch specific mmap attributes
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From: David Miller on 7 Apr 2010 03:10 From: KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com> Date: Wed, 7 Apr 2010 15:03:45 +0900 (JST) > I'm not against changing kernel internal. I only disagree mmu > attribute fashion will be become used widely. Desktop already uses similar features via PCI mmap attributes and such, not to mention MSR settings on x86. So I disagree with your assesment that this is some HPC/embedded issue. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: KOSAKI Motohiro on 7 Apr 2010 03:20 > From: KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com> > Date: Wed, 7 Apr 2010 15:03:45 +0900 (JST) > > > I'm not against changing kernel internal. I only disagree mmu > > attribute fashion will be become used widely. > > Desktop already uses similar features via PCI mmap > attributes and such, not to mention MSR settings on > x86. Probably I haven't catch your mention. Why userland process need to change PCI mmap attribute by mmap(2)? It seems kernel issue. > So I disagree with your assesment that this is some > HPC/embedded issue. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: David Miller on 7 Apr 2010 03:20 From: KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com> Date: Wed, 7 Apr 2010 16:14:29 +0900 (JST) >> From: KOSAKI Motohiro <kosaki.motohiro(a)jp.fujitsu.com> >> Date: Wed, 7 Apr 2010 15:03:45 +0900 (JST) >> >> > I'm not against changing kernel internal. I only disagree mmu >> > attribute fashion will be become used widely. >> >> Desktop already uses similar features via PCI mmap >> attributes and such, not to mention MSR settings on >> x86. > > Probably I haven't catch your mention. Why userland process > need to change PCI mmap attribute by mmap(2)? It seems kernel issue. It uses PCI specific fd ioctls to change the attributes. It's the same thing as extending the mmap() attribute space, but in a device specific way. I think evice and platform specific mmap() attributes are basically inevitable, at any level, embedded or desktop or whatever. The fact that we've hacked around the issue with device specific interfaces like the PCI device ioctls, is no excuse to not tackle the issue directly and come up with something usable. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Benjamin Herrenschmidt on 7 Apr 2010 05:00
On Wed, 2010-04-07 at 00:03 -0700, David Miller wrote: > > I'm not against changing kernel internal. I only disagree mmu > > attribute fashion will be become used widely. > > Desktop already uses similar features via PCI mmap > attributes and such, not to mention MSR settings on > x86. This is a very good point, we've had all sort of trouble hacking that in for PCI mmap, between trying to get write combine in, which we got on /proc via a tweak I think we never got over to sysfs, and the ability to control cachability, for which we used to have O_SYNC hacks in /dev/mem, I think there is room for some nice and clean set of attributes here. Cheers, Ben. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |