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Groups > linux.debian.kernel > #60186

Revisiting x32 ABI state

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Moin

After almost four years and due to recent changes in the syscall path,
I'd like to revisit our current handling of the x32 ABI.

Currently we disable support for the x32 ABI on runtime, enabling it
needs a kernel command line parameter.  This Debian specific change was
done due to concerns of ABI specific problems with the pretty new code.

In 4.15.2 the syscall path was cleaned up.  The so called "fast-path"
was dropped completely, it didn't provide much of a fast path anymore
because of the whole Spectre and Meltdown stuff.  Also our patch made
inline patches of the fast path, to remove the overhead of the checks.

I think after that four years we shoud revisit that change.  Do we still
think x32 may be a problem?  Does the patch introduce runtime latency
due to it's not longer inline patched form?

Regards,
Bastian

-- 
There is a multi-legged creature crawling on your shoulder.
		-- Spock, "A Taste of Armageddon", stardate 3193.9

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Revisiting x32 ABI state Bastian Blank <waldi@debian.org> - 2018-02-11 11:20 +0100
  Re: Revisiting x32 ABI state Ben Hutchings <ben@decadent.org.uk> - 2018-02-11 23:30 +0100

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