Kernel 4.12

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Kernel downloads for the "Development stream"

Download Description
upstream kernel 4.12 kernel 4.12 - upstream with feature descriptions.
linux-4.12-s390-message-catalog.tgz / MD5 "Development Stream" kernel 4.12 - message-catalog (optional)

2017-11-28: kernel 4.12 - upstream (feature description)

To download the linux-4.12.tar.gz visit:

The upstream kernel 4.12 contains the following functionality developed by the Linux on Z and LinuxONE development team:

Improve garbage collection.
The guarded-storage facility is designed to improve the performance for the garbage-collection of languages like Java. Through a kernel interface, user space programs can enable the facility for specific threads of a process.
This feature requires an IBM z14 or higher.

Measure workload with hardware-based performance counters.
With this feature, you can access counters from the MT-diagnostic counter set that is available with IBM z13. You can also specify z13 specific counters using their symbolic event names and obtain counter descriptions with the lscpumf utility.
For documentation see Device Drivers, Features, and Commands, Chapter 'Using the CPU-measurement facilities'.

Disk Encryption using Secure Keys.
With kernel 4.12, a new in-kernel crypto API module is provided to perform protected key AES (paes) cryptographic operations. You can use paes for setting up disk encryption with dm-crypt. Use the new zkey utility to generate secure keys and use them for your disk encryption. Secure keys protect the effective encryption key by encrypting the effective key with a master key of an IBM CryptoExpress card. With this feature, the effective encryption key is never exposed to the operating system or any application. The paes module converts the secure key into a protected key to perform AES cryptographic operation at CPU speed with CPACF.
This feature requires an IBM zEnterprise 196 or higher and an IBM Crypto Express adapter.
For documentation see

The true random number generator (TRNG) device driver provides user-space applications with random data generated from the IBM Z hardware CPACF true random source.
With zMidas there comes a CPACF extension (MSA 7) which is providing support for the generation of random data based on a true hardware random implementation (’TRNG’ - true random number generation). Kernel 4.12 has a new s390 specific device driver s390-trng which is exploiting this new TRNG and contributing to the existing common hwrng device driver within the kernel. So /dev/hwrng and the new /dev/trng both are served by the new trng device driver. Also the arch_random_ API which is used within the kernel to pull small amounts of random data is served by the new TRNG instruction now.
This feature requires an IBM z14 or higher.
For documentation see Device Drivers, Features, and Commands, Chapter 'True random-number generator device driver'.

2017-11-28: "Development Stream" kernel 4.12 message catalog (feature - optional patch)

linux-4.12-s390-message-catalog.tgz / MD5 ... recommended (2017-11-28)

This patch contains:

Kernel message catalog.
Add support for automatic message tags to the printk macro families dev_xyz and pr_xyz. The message tag consists of a component name and a 24 bit hash of the message text. For each message that is documented in the included kernel message catalog a man page can be created with a script (which is included in the patch). The generated man pages contain explanatory text that is intended to help understand the messages.

Note that only s390 specific messages are prepared appropriately and included in the generated message catalog.

This patch is optional as it is very unlikely to be accepted in upstream kernel, but is recommended for all distributions which are built based on the 'Development stream'.