The brand new release of Ubuntu 21.04, the Hirsute Hippo, was released on April 22, 2021. It’s an interim release of the popular Linux distribution, with only nine months of support from Canonical. So is it worth upgrading to?

The Hirsute Hippo

The Hirsute Hippo hit the streets (or mud holes) on April 22, 2021. Either way, the latest version of the enormously popular Ubuntu Linux distribution from Canonical is available for download. Ubuntu 21.04 is an interim release, which means that it receives support for nine months only.

Canonical releases a build of Ubuntu every six months, one in April and one in October. Every two years, one of these builds is designated a Long Term Support (LTS) release. LTS releases are supported for five years and are considered enterprise-grade. The other releases—the interim builds—are for those who want to have the latest release of Ubuntu and the newest selection of applications, and for whom stability is of secondary importance.

To be fair to Canonical, the interim builds are always pretty stable. They sometimes need a little time to settle down as the post-launch patches are rolled out, but they do get onto an even keel very quickly. Because the interim builds are used as proving grounds for the software, features, and innovations that will eventually be included in the next LTS build, there’s a small residual risk in using them.

Some of the hoped-for features, such as the GNOME 40 desktop environment and the GTK 4 development toolkit, didn’t make it into Hirsute Hippo. GNOME 40 has a lot of changes in it, so there were concerns about upgrading. Rather than risking introducing something that could negatively impact the desktop experience, the GNOME extensions, and the Yaru theme, GNOME 40 was dropped from this release. Ubuntu 21.04 sticks with GTK 3 and GNOME 3.38.

That’s not a bad thing. Even in an interim build, there’s no place for recklessness. And in fact, the new content in GNOME 40 isn’t as much as you might expect from the jump in the build version number. The GNOME versioning scheme was becoming unwieldy. The build number was bumped up to 40 to start a new numbering scheme. It doesn’t represent a major development or a lot of new content, so there was even less reason to include it.

But enough about what didn’t make the cut. What’s new in Ubuntu 21.04?

Linux Kernel 5.11

There’s been some confusion around the new features in kernel 5.11. When Linus Torvalds announced the release of the new kernel on St. Valentine’s day, he said, “It’s a smaller-than-average set of commits from rc7 to final.” However, that doesn’t mean that there’s not much in this release. It just means that between the seventh final release candidate and the release build, there were very few commits. So there was very little last-minute code-churn, which is a good thing. But there’s plenty in this kernel that is of interest.

Software Guard Extensions: Intel’s Software Guard Extensions (SGX) feature is now supported. SGX allows for the creation of secure, encrypted memory zones called enclaves. Enclaves are opaque to external code. Normal code can make requests to the enclaves, but they cannot directly access their contents. Code running inside the enclave services the requests from non-enclave code. Intel is promoting enclaves as a way of protecting private and sensitive items, such as encryption keys from a malicious or compromised kernel. AMD Processor Enhancements: AMD processors also receive some attention, with performance and management enhancements in the kernel. There’s power-management support for AMD’s Zen CPUs, for example. Syscall User Dispatch: A new system call interception scheme designed to improve the efficiency of emulators like Wine has been implemented. Wine needs to frequently swap between Windows-based and Linux-based code. The new call trapping and rerouting routines are expected to yield a significant performance boost. Constant-Action Bitmaps: The  seccomp() system call is used to define what system calls a user space process can invoke in kernel space. The arguments to system calls used to be examined to see whether the call was allowed, or whether the process or thread should be killed. This provided security to the system by reducing the number of ways that the kernel could be attacked by malicious software. The new scheme reduces the overhead of this functionality by using bit-mapped memory regions that hold binary flags and function similarly to allow-lists, block-lists, and kill-lists.

Of course, a new kernel includes many bug fixes, security improvements, and support for specific hardware use cases. Support has been added or improved for:

handling USB4 and Thunderbolt. hardware detection in Lenovo ThinkPad laptops. ASUS gaming laptop keyboards. detection of PCI subsystems using the 64 gigatransfers per second (GT/s) link speed. reading the sensors in Corsair Power Supplies.

Visual Tweaks

Hirsute Hippo ships with a selection of new wallpapers featuring our celebrity Hippopotamidae.

The purple-based design palette remains, and the default theme is still Yaru. There are some tweaks and changes, however. Hirsute Hippo defaults to a dark theme by default, but it isn’t global. It’s selectively applied to some desktop elements—the calendar and the system menu, for example—but not to everything.

The system menu has smaller separators between the menu sections, and the arrowhead or triangle indicator used to expand sections is now a chevron.

The orange highlight bar in the Nautilus file browser sidebar is replaced with a much more subdued, gray-tinted highlight. A selected icon still gets picked out in the familiar orange.

Many of the icons have been updated. Most document types now sport a folded-down corner. The LibreOffice icons use fewer colors and look less cluttered.

Wayland Is the Default Display Server

Canonical switched to using Wayland as the display server in Ubuntu 17.10 but reverted to using the X.Org X11 server in subsequent releases. Hippo sees the reintroduction of Wayland as the default display server—unless you’re using Nvidia graphics hardware. If Nvidia hardware is detected, you’ll remain on X.Org. If you find any issues with Wayland, you can force your system to use X.Org.

Use this command to edit the GNOME display manager config file:

To switch back to X.Org, delete the hash mark “#” from the start of the highlighted line and reboot.

In previous releases of Ubuntu, a cog icon on the login screen gave access to options to choose which display server you wanted to use. That cog icon wasn’t present in the beta version of Hirsute that Hippo used to research this article. It’ll be interesting to see whether it reappears in the final release.

Files on the Desktop Are Back

If you want to drop a file on the desktop, you can. This functionality was removed in GNOME 3.28. Some people want the ability to place files on the desktop, while others don’t. But removing their ability to choose wasn’t a popular move.

The GNOME extension Desktop Icons NG (DING) was created to allow people to use the desktop however they like. Hirsute Hippo comes with the DING extension installed, so you have a choice once again.

Updated Software

As always, many of the native software packages have been refreshed and updated. Here are the versions of some of the major applications included in Ubuntu 21.04:

Firefox: 87. 0 Thunderbird: 78. 8. 1 LibreOffice: 7. 1. 2. 2 Nautilus (Files): 3. 38. 2-stable Kernel: 5. 11. 0-13-generic Bash: 5. 1. 4 gcc: 10. 2. 1 20210401 OpenSSL: 1. 1. 1j 16 Feb 2021 GNOME: 3. 38. 4

Home Directory Security

Apparently, hippos prefer privacy. Home directories in Ubuntu 21.04 are more secure by default. In previous versions of Ubuntu, every user had read and execute access to every other users’ home directory. Ubuntu 21.04 sets the permissions for home directories to 750 instead of 755. The owner and group permissions remain as they were, but the permissions for all other users have been removed.

750: The new permissions. rwxr-x— . Read, write, and execute for the owner and read and execute for group members, but no access for everyone else. 755: The old permissions. rwxr-xr-x . Read, write, and execute for the owner, read and execute for group members, and read and execute for everyone else.

If you do a fresh install of Ubuntu 21.04, a new set of permissions are used for your home directory. If you do an upgrade, the permissions on existing users’ home directories won’t be changed. Newly created home directories will receive the new set of default permissions.

A Worthwhile Upgrade?

The Hirsute Hippo behaved well in testing and feels like a solid, stable build. What it lacks in surface glitter it makes up for with many significant changes beneath the hood—even without GNOME 40. The 5.11 kernel, refreshed applications, and system-wide bug fixes and security enhancements are all advantageous. The change of permissions on the home directories is a welcome change, too. It’s nothing that you couldn’t do by hand in other releases, but how many actually bothered?

Canonical estimates that 95% of Ubuntu installations are LTS versions. No doubt they’ll stick with Ubuntu 20.04 LTS “Focal Fossa” until 22.04 comes along. As for the other 5%? If I was running an Ubuntu interim release like Ubuntu 20.10 “Groovy Gorilla,” I’d upgrade to 21.04. There are enough significant and beneficial engineering improvements to make it worthwhile.

If you’re undecided, remember that you can always spin up a virtual machine in VirtualBox and take the Hippo for a risk-free test spin—or a slow waddle.