What's New in Linux kernel 5.3 - Graphics Drivers, Virtualization, and Modifications in the Network Subsystem

We will tell about updates and see what changes are already being prepared for the next version.

Photos – Ian Parker – Unsplash

Graphics Driver Update

Linux kernel 5.3 added support for AMD Navi GPUs (RX5700) in the amdgpu driver. All binary microcodes necessary for initializing the video cards were placed (some time after the update was released) in the repository linux-firmware.git. Previously, “binaries” had to be downloaded separately – from the personal site of Alex Deucher, the lead amdgpu maintainer.

Also, the core developers improved the performance of the Vega12 and Vega20 GPUs, for which they added additional memory and power management capabilities.

There are a number of updates from the developers of the Nouveau project, who are responsible for the free Nvidia drivers. They added support for Turing TU116. This is a graphics processor installed on GeForce GTX 1660 Ti cards. The project maintainer noted that along with the new chipset definitions in the Nouveau driver, they fixed bugs related to memory leaks and KMS operation.

So far, nothing is known about the implementation of reclocking for graphics cards in the GTX 900 Maxwell series. Although the situation may change soon. In mid-August, Nvidia submitted the latest documentation for its products to open source. And the information needed to configure automatic frequency control should be provided later.

Network subsystem

Linux now supports IPv4 processing in the range 0.0.0.0/8. The introduction of this subnet made it possible to allocate another 16 million IP addresses. Also for IPv4 and IPv6, the nexthop mechanism has been added. It increases the scalability of routing tables. According to the core developers, the new solution loads 740 thousand routes in 4.3 seconds.

Also, the netfilter firewall with nftables received a mechanism for accelerating packet filtering – the Flow Block API was added to the drivers. Now it’s possible to make entire tables of rules to the network adapters — there is support for simple metadata of the L3 and L4 protocols, as well as matching by the addresses and network ports of the sender / receiver and the type of protocol.

Virtualization

The core includes the ACRN hypervisor, which is used in IoT devices and embedded technology. It is being developed based on Intel's lightweight hypervisor.

Photo – Casey Horner —Unsplash

Linux also got time travel mode. It makes it possible to speed up or, conversely, slow down time in a virtual UML environment. This feature simplifies the debugging of time-sensitive code. In addition, the developers added the time-travel-start parameter – it starts the VM system clock from the required moment.

New periphery

The SPI driver for MacBook and MacBook Pro keyboards and trackpads, released since 2015, has been added to the Linux kernel. Apple did not disclose documentation for the SPI standard, but the kernel development team managed to reverse engineer it and write a driver. Although work on the project has not yet been completed, there are still a few teams whose information is encrypted.

Also in Linux kernel 5.3 added support: steering Saitek R440 Force Feedbackgraphic tablets Ugee Rainbow CV720, Wacom MobileStudio Pro and Wacom intuos pro small (2nd generation), as well as the receiver Logitech MX3000 (27 MHz).

What was removed

Before the release of the new kernel version, Linus Torvalds in the LKML newsletter reminded the IT community of the main rule for developing the Linux kernel: changes should not disrupt existing applications. After he said that he decided to abandon the patch that optimizes ext4.

He reduced the number of accesses to the drive by disabling the proactive reading of the inode table with small I / O requests. But optimization led to an unexpected error – the system began to “freeze” when the getrandom () generator started, which uses disk activity to generate random numbers. Therefore, ext4 optimization was postponed until the bug was fixed.

Also, after discussions in LKML, the developers announced that they were phasing out support for the FMC bus – engineers from CERN were responsible for it for seven years. FMC was used to link FPGAs and other devices with an I / O interface.

They decided to rewrite the system from scratch, since it found serious architectural flaws. It will appear in future releases of the Linux kernel.

What to expect in kernel 5.4

It will update the monitoring system for AMD processors – hwmon. So far, due to a hardware developer error, the solution shows incorrect temperature data for the Ryzen 3000. Also in kernel 5.4 they will add support for the Qualcomm Snapdragon 855 chip and Intel Icelake Thunderbolt.

Photos – Marvin Heilemann – Unsplash

The upcoming kernel version will introduce a patch that optimizes the operation of a number of 64-bit Windows games for Wine, CrossOver and Valve Proton. UMIP instructions are executed in user space, which causes errors in working under Wine. The new version of Linux will eliminate this drawback.

Of course, there will be fresh updates that solve the problem of 2038. Developers regularly make changes to system calls, and the upcoming kernel version should not be an exception.

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