Kernel: Remembering Bonnie and LWN Articles Released From Paywall
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Tim Bray ☛ Remembering Bonnie
Filesystems are one of the pieces of software that computers need to run, where “computers” includes your phone and laptop and each of the millions of servers that drive the Internet and populate the cloud. There are many flavors of filesystem and people who care about them care a lot.
One of the differences between filesystems is how fast they are. This matters because how fast the apps you use run depends (partly) on how fast the underlying filesystems are.
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LWN ☛ Two approaches to tightening restrictions on loadable modules
The kernel's loadable-module facility allows code to be loaded into (and sometimes removed from) a running kernel. Among other things, loadable modules make it possible to run a kernel with only the subsystems needed for the system's hardware and workload. Loadable modules can also make it easy for out-of-tree code to access parts of the kernel that developers would prefer to keep private; this has led to many discussions in the past. The topic has returned to the kernel's mailing lists with two different patch sets aimed at further tightening the restrictions applied to loadable modules.
When the static kernel image is linked, references to symbols (the names of functions and data structures) are resolved using the entire global namespace. Loading a module also involves a linking step, but modules do not have access to the full namespace; instead, they can only access symbols that have been explicitly exported to them. There are two sets of exported symbols: those that are available to any loadable module, and those that are only available to modules that declare a GPL-compatible license. Access to symbols is the primary means by which the capabilities of loadable modules are limited, so it is not surprising that both patch sets make changes to that mechanism.
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LWN ☛ Dancing the DMA two-step
Direct memory access (DMA) I/O is simple in concept: a peripheral device moves data directly to or from memory while the CPU is busy doing other things. As is so often the case, DMA is rather more complicated in practice, and the kernel has developed a complicated internal API to support it. It turns out that the DMA API, as it exists now, can affect the performance of some high-bandwidth devices. In an effort to address that problem, Leon Romanovsky is making the API even more complex with this patch series adding a new two-step mapping API.
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LWN ☛ Development statistics for [Linux] 6.12
Linus Torvalds released the 6.12 kernel on November 17, as expected. This development cycle, the last for 2024, brought 13,344 non-merge changesets into the mainline kernel; that made it a relatively slow cycle from this perspective, but 6.12 includes a long list of significant new features. The time has come to look at where those changes came from, and to look at the year-long LTS cycle as well.
The 6.12 kernel included work from 2,074 developers; this is not a record (that is 2,090 in 6.2), but is close. Of those developers, 335 made their first contribution to the kernel during this cycle; that is a record for the Git era (and probably before as well).