Linux kernel 5.1 - what's known about changes
The jubilee version of the Linux 5.0 kernel was released in early March. But work on kernel 5.1 is already underway. In this material, we consider a number of innovations that are worth waiting for in this version.
/ Flickr / ayu oshimi / CC BY-SA
Linux supports ELF binaries since the first version of the kernel. After 25 years, a.out plan to transfer to the category of obsolete technologies (deprecated). The developers say that this is a necessary procedure, because in a long time the code began to "rot . "
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Linus Torvalds separately stressed that none of the existing compilers does not create a.out format binaries, so there is no point in it anymore.
The rejection of a.out will take place in two stages. In Linux 5.1, the core dumping code will be removed - approximately 500 lines . According to Linus, it is extremely unlikely that someone will need to deal with legacy code, and users who are still generating a.out executable files will have time to restructure their business processes.
In subsequent releases, support will be completely discontinued, but only if there is no person in the community who will take care of the format.
Several changes will be made to the patch of Retpoline to protect against Specter v2 attacks. It uses a special sequence of instructions that blocks the speculative execution mechanism in the processor. Developers plan to increase the threshold for generating indirect calls from branch operators from five to twenty. In some cases, this will increase productivity by 20%.
Also, the 5.1 kernel will receive a new PR_SPEC_DISABLE_NOEXEC flag, which disables protection against Specter v4 vulnerability in all child processes running on the server. It is associated with the memory disambiguation function, which allowed the extraordinary execution of commands. According to experts, the flag automates the check for shutting down the patch and will speed up servers with a large number of simultaneously running processes. We wrote more about this in one of the previous materials .
New features that optimize Linux servers can affect the popularity of this OS in the cloud. We collected statistics in 1cloud - Windows remains the most popular operating system in the cloud among our customers (79%). The share of Linux is 20%. In the future, we expect that the second OS will play a few positions in the market. We also give a graph of the distribution of shares among Linux distributions (Ubuntu remains the most popular distribution among our clients - 45%, followed by CentOS with 28% and Debian with 26%.
In one of the threads on Hacker News, residents noted that Linux has always had difficulties with supporting iron. But in 5.1 many drivers for audio equipment will be added.
For example, a driver will appear for the sound card Fireface UCX , oriented to work in recording studios and concert halls. Also add the MediaTek BTCVSD driver for the Bluetooth chip, which was proposed by the developers from MediaTek.
We should expect support for Asahi Kasei Microdevices AK4497, Cirrus Logic CS4341 / CS35L26 and Google ChromeOS embedded controllers. The list includes Ingenic JZ4725B, MT8183 and MT6358, NXP MICFIL, Rockchip RK3328, Spreadtrum DMA controllers and many others.
/ Flickr / Christopher Michel / CC BY
According to Phoronix, developers can return the ability to use permanent memory as RAM in Linux 5.1. In particular, Optane NVDIMM (made using 3D Xpoint technology) on the DDR4 bus can be “turned” into random access memory.
Read more about the work being done in this direction in the LKML thread . Linus is now waiting for an explanation about the behavior of Optane from developers from Intel. Only after receiving them will he decide whether to include the new function in the 5.1 kernel.
You can still expect patches that solve the problem of 2038 . On January 19, 2038, the time value will cease to “fit” into a 32-bit integer with a sign. This will cause massive disruptions in the programs. Therefore, developers are gradually making changes to the corresponding system calls - the new version of the kernel will not be an exception.
More information about potential changes in the Linux kernel code can be expected in the near future. We will continue to write about them in subsequent articles.
/ Flickr / ayu oshimi / CC BY-SA
Stop supporting a.out
Linux supports ELF binaries since the first version of the kernel. After 25 years, a.out plan to transfer to the category of obsolete technologies (deprecated). The developers say that this is a necessary procedure, because in a long time the code began to "rot . "
')
Linus Torvalds separately stressed that none of the existing compilers does not create a.out format binaries, so there is no point in it anymore.
The rejection of a.out will take place in two stages. In Linux 5.1, the core dumping code will be removed - approximately 500 lines . According to Linus, it is extremely unlikely that someone will need to deal with legacy code, and users who are still generating a.out executable files will have time to restructure their business processes.
In subsequent releases, support will be completely discontinued, but only if there is no person in the community who will take care of the format.
Make changes to the Specter patches
Several changes will be made to the patch of Retpoline to protect against Specter v2 attacks. It uses a special sequence of instructions that blocks the speculative execution mechanism in the processor. Developers plan to increase the threshold for generating indirect calls from branch operators from five to twenty. In some cases, this will increase productivity by 20%.
Also, the 5.1 kernel will receive a new PR_SPEC_DISABLE_NOEXEC flag, which disables protection against Specter v4 vulnerability in all child processes running on the server. It is associated with the memory disambiguation function, which allowed the extraordinary execution of commands. According to experts, the flag automates the check for shutting down the patch and will speed up servers with a large number of simultaneously running processes. We wrote more about this in one of the previous materials .
New features that optimize Linux servers can affect the popularity of this OS in the cloud. We collected statistics in 1cloud - Windows remains the most popular operating system in the cloud among our customers (79%). The share of Linux is 20%. In the future, we expect that the second OS will play a few positions in the market. We also give a graph of the distribution of shares among Linux distributions (Ubuntu remains the most popular distribution among our clients - 45%, followed by CentOS with 28% and Debian with 26%.
Add audio drivers (many)
In one of the threads on Hacker News, residents noted that Linux has always had difficulties with supporting iron. But in 5.1 many drivers for audio equipment will be added.
For example, a driver will appear for the sound card Fireface UCX , oriented to work in recording studios and concert halls. Also add the MediaTek BTCVSD driver for the Bluetooth chip, which was proposed by the developers from MediaTek.
We should expect support for Asahi Kasei Microdevices AK4497, Cirrus Logic CS4341 / CS35L26 and Google ChromeOS embedded controllers. The list includes Ingenic JZ4725B, MT8183 and MT6358, NXP MICFIL, Rockchip RK3328, Spreadtrum DMA controllers and many others.
/ Flickr / Christopher Michel / CC BY
What else to expect in Linux kernel 5.1
According to Phoronix, developers can return the ability to use permanent memory as RAM in Linux 5.1. In particular, Optane NVDIMM (made using 3D Xpoint technology) on the DDR4 bus can be “turned” into random access memory.
Read more about the work being done in this direction in the LKML thread . Linus is now waiting for an explanation about the behavior of Optane from developers from Intel. Only after receiving them will he decide whether to include the new function in the 5.1 kernel.
You can still expect patches that solve the problem of 2038 . On January 19, 2038, the time value will cease to “fit” into a 32-bit integer with a sign. This will cause massive disruptions in the programs. Therefore, developers are gradually making changes to the corresponding system calls - the new version of the kernel will not be an exception.
More information about potential changes in the Linux kernel code can be expected in the near future. We will continue to write about them in subsequent articles.
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Source: https://habr.com/ru/post/444078/
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