Linux 5.18 comes as a “small revolution”

Linux 5.18 comes as a “small revolution”
Written by insideindyhomes

In the night from Sunday to Monday, Linus Torvalds released the latest Linux kernel version 5.18. The new kernel had previously been treated as a comprehensive but “only” maintenance release. On closer inspection, apart from driver updates and bug fixes, some interesting new features have been added, some of which point the way and some of which are even the subject of quite controversial discussion.

Linux 5.18 offers the necessary piece of code to be able to use Intel’s “Software Defined Silicon” (SDSi). SDSi is a mechanism for unlocking hardware features in future processors from the Santa Clara chipmaker. The new Linux kernel offers simple operations for this, on the one hand to install authentication certificates in the CPU and on the other hand to enable properties (capability) in the hardware. The certificates serve as a key to enable the respective hardware properties to be unlocked at all. The respective capability can only be activated and used once the appropriate certificate has been installed.

If too many attempts are made to install an incorrect certificate, the hardware blocks all further attempts. To do this, the hardware runs a counter that no longer allows any further attempts when a value is exceeded. A new activation attempt can only be attempted after a cold start.

Intel is trying to breathe new life into an old business model. In the mainframe environment, it was and is customary to deliver systems that are fully equipped on the hardware side. However, the usable scope of services is only defined by the purchased licenses. The mainframe manufacturer can activate, deactivate or even repurpose hardware via microcode updates. The situation is similar with SDSi. If the appropriate certificates, i.e. license keys, are installed, certain hardware components can be activated and used.

It is currently still unclear which hardware properties this will affect. It is also not clear whether licenses will be granted permanently or whether a subscription model will come. The latter could flirt with models that are already emerging in the automotive sector. For example, a Tesla that is fully equipped in terms of hardware can only be used to its full extent if the relevant features are activated. The activation period can be linked to a subscription.

This model got the tempers of the Linux community boiling. Open source should give the user full transparency and control over the system. This is basically still the case with the license model à la SDSi. However, the usable range is stretchable.

Anyone who also uses Linux with sustainability as a basic idea on older hardware faces new questions and challenges. How long can features be purchased on older processors? How long can subscriptions be extended? This shakes the open source world view and triggers philosophical debates.

The new driver for SDSi was widely discussed in advance, both in the community and in articles in specialist media. For example at LWN, which looks at the topic from the point of view of free software. The Register, on the other hand, asks very practically what will unlock SDSi or what will be behind a “paywall”. However, the British IT news portal did not find a concrete answer.

From a technical point of view, there is little to be said against including the SDSi driver in the kernel. The way the driver works is very simple, since the interface to the hardware is also very simple. The philosophical discussion weighs heavier. SDSi fuels the demand for open source hardware in the community. Free software should be on free hardware.

This is why some people ask whether an SDSi driver has any place in the Linux kernel at all. But the argument is purely theoretical and philosophical. In practical terms, ditching the SDSi driver would not solve the problem either. The driver is so simple that any distributor or hardware vendor could include it in their own kernel.

It is currently unclear where the journey with the “buying” of hardware features is going. After all, Intel has so far kept a low profile with regard to the switchable properties. It is also unclear whether other manufacturers such as AMD will follow suit. The hardware license issue is not new for Linux either. On the IBM mainframe System z, Linux for s390x is also faced with the issue. However, Intel aims at the native architecture of Linux, which was created on the i386. In addition, the majority of Linux systems run on processors derived from x86. The open source scene saw this as a wake-up call. The topic will keep the community apart from the SDSi driver busy for a long time. Whether it actually brings new impetus to open source hardware will ultimately depend on Intel’s concrete plans.

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