KernelTrap - Intel

Quote: The Real Bug

Jeremy — Tue, 30 Sep 2008 15:38:36 +0000

"The _real_ bug is clearly in the hardware design that allows you to brick those things without apparently even having a lock bit. I'm hoping Intel doesn't treat this as just a software bug. Some hw designer should be thinking hard about which orifice they put their head up in."

2.6.26-rc7, "Mainly Drivers And Arch Updates"

Jeremy — Sat, 21 Jun 2008 07:04:25 +0000

"Another week, another -rc," began Linux creator Linus Torvalds, announcing the 2.6.26-rc7 Linux kernel, "and as usual, it's mainly drivers and arch updates - over 90% of changes are in one or the other." He continued:

"A big part of it (about two thirds of the driver update, in fact) is a late-dropping AGP/DRM update that adds support for some new Intel and ATI graphics cards. And a big part of the arch update is the inevitable def_config updates, of course. I'm not all that happy about the timing of the support for the new cards, but at the same time I also hate delaying new drivers. Obviously the hope is that it can't cause any regressions, since the added code is almost entirely for stuff that simply wasn't supported at all before."

Linus concluded, "if you ignore the driver and arch updates, the rest is pretty minor. About half is in networking, and half of the remaining is filesystems updates (mainly ocfs2). And random smatterings elsewhere, like some scheduler updates."

LatencyTop, Identifying System Latency

Jeremy — Fri, 18 Jan 2008 20:28:35 +0000

"Slow servers, Skipping audio, Jerky video --everyone knows the symptoms of latency. But to know what's really going on in the system, what's causing the latency, and how to fix it... those are difficult questions without good answers right now," began Arjan van de Van, announcing version 0.1 of LatencyTop, "a tool for developers to visualize system latencies." He continued:

"LatencyTOP is a Linux tool for software developers (both kernel and userspace), aimed at identifying where system latency occurs, and what kind of operation/action is causing the latency to happen. By identifying this, developers can then change the code to avoid the worst latency hiccups.

"There are many types and causes of latency, and LatencyTOP focus on type that causes audio skipping and desktop stutters. Specifically, LatencyTOP focuses on the cases where the applications want to run and execute useful code, but there's some resource that's not currently available (and the kernel then blocks the process). This is done both on a system level and on a per process level, so that you can see what's happening to the system, and which process is suffering and/or causing the delays."

DMA Framework

Jeremy — Mon, 29 Oct 2007 02:19:36 +0000

"This patch corrects what I hope are invalid assumptions about the DMA engine layer: Not only Intel(R) hardware can do DMA, and DMA can be used for other things than memcpy and RAID offloading," Haavard Skinnemoen noted, submitted a small patch against the DMADEVICES Kconfig option. He added, "Don't get me wrong; I think Intel deserves lots of respect for creating this framework. But this is also why I got a bit disappointed when I discovered that it seems to be less generic than I initially hoped." Haavard continued:

"DMA controllers, which may support plain memcpy acceleration in addition to more traditional 'slave DMA', are very common in SoC devices, and I think Linux needs a common framework for it. The existing DMA Engine framework seems to come pretty close already, but I think it needs more input from the embedded crowd before it can be completely usable on a large number of embedded systems."

Manageability Engine Interface

Jeremy — Thu, 25 Oct 2007 01:28:27 +0000

"The Manageability Engine Interface (aka HECI) allows applications to communicate with the Intel(R) Manageability Engine (ME) firmware. It is meant to be used by user-space manageability applications to access ME features such as Intel(R) Active Management Technology, Intel(R) Quiet System Technology and ASF," Anas Nashif began, describing a new driver for accessing services found in most recent Intel desktop chipsets. Andrew Morton offered an initial review of the patch and asked for additional information, "why do we want to include this code in Linux? What value has it to our users, etc? Basically: tell us more stuff.". Anas added:

"The core hardware architecture of Intel Active Management Technology (Intel AMT) is resident in firmware. The micro-controller within the chipset's graphics and memory controller (MCH) hub houses the Management Engine (ME) firmware, which implements various services on behalf of management applications. Additionally, flash memory houses system BIOS, code used by the management engine, and a third-party data store (3PDS) that enables applications to store information as needed in non-volatile memory."

Power Saving Projects

Jeremy — Fri, 21 Sep 2007 08:53:55 +0000

"Intel's Open Source Technology Center is pleased to announce the LessWatts.org project, an open source project for saving power on Linux," began an email posted to the lkml by Arjan van de Ven. The announcement continued:

"LessWatts.org is a place to bring users, developers and distribution makers together around power reduction for linux machines, from mobile to desktop to server to datacenter. LessWatts.org is about a system-level approach to power savings, from the lowest level device drivers in the kernel to the most advanced desktop applications. LessWatts.org is about things you can do to reduce power usage. LessWatts.org is about longer battery life, a lower airconditioning bill, about reducing the impact of computers on the environment."

The announcement went on to note, "at this time of launching the LessWatts.org project, the technology development projects are those that Intel has started, is involved in or has just started working on, such as PowerTOP, Tickless Idle, Graphics and various link power management techniques. We'd like to invite all developers and projects that focus on power saving to join the LessWatts.org effort and community."

OpenBSD: Intel Core 2 Bugs

Jeremy — Sat, 30 Jun 2007 20:37:59 +0000

Theo de Raadt [interview] described an active effort by OpenBSD developers to work around "serious bugs in Intel's Core 2 cpu". He went on to explain, "these processors are buggy as hell, and some of these bugs don't just cause development/debugging problems, but will *ASSUREDLY* be exploitable from userland code. As is typical, BIOS vendors will be very late providing workarounds / fixes for these processors bugs. Some bugs are unfixable and cannot be worked around. Intel only provides detailed fixes to BIOS vendors and large operating system groups. Open Source operating systems are largely left in the cold." He provided a link to the full errata (in PDF format) as well as a graphical overview, summarizing:

"Note that some errata like AI65, AI79, AI43, AI39, AI90, AI99 scare the hell out of us. Some of these are things that cannot be fixed in running code, and some are things that every operating system will do until about mid-2008, because that is how the MMU has always been managed on all generations of Intel/AMD/whoeverelse hardware. Now Intel is telling people to manage the MMU's TLB flushes in a new and different way. Yet even if we do so, some of the errata listed are unaffected by doing so.

As I said before, hiding in this list are 20-30 bugs that cannot be worked around by operating systems, and will be potentially exploitable. I would bet a lot of money that at least 2-3 of them are."

OpenBSD: Copyrights versus Contracts

Jeremy — Fri, 25 May 2007 16:54:06 +0000

"ANY rule which reduces your rights is unacceptable," explained Theo de Raadt [interview] in a brief discussion on the OpenBSD -misc mailing list, "especially when the full consequences of such a set of rules may be unclear -- which it always is." The comment was in response to a query about why Intel's firmware was considered non-free. Theo went on to explain:

"Normal free software has no 'contract law' issues, because it is simply given away under 'copyright law with almost all author's rights revoked'. Contract law works differently, because it is based more on the principle of 'you got something, now you have to give something back'. The minute you see a URL like that explaining things in such a way, you should realize that the addition of 'rules' means you are in a different legal system.

"Copyright has no way to apply such rules, therefore [the Intel firmware] is not free."