Date: Thu, 15 Jul 2021 19:06:47 -0700 From: Mark Millard via freebsd-arm <freebsd-arm@freebsd.org> To: Michael Tuexen <tuexen@freebsd.org> Cc: freebsd-arm@freebsd.org Subject: Re: register x18 Message-ID: <BFF3BCE7-3387-4A7C-A71C-890223CDDF18@yahoo.com> In-Reply-To: <86EC9C12-F90C-4D0C-BFA3-41986C9F07B5@freebsd.org>
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On 2021-Jul-15, at 17:40, Michael Tuexen <tuexen at freebsd.org> wrote: > Dear all, > > register x18 seems to be special. What is it used for in FreeBSD? > > Best regards > Michael https://developer.arm.com/documentation/den0024/a/The-ABI-for-ARM-64-bit-Architecture/Register-use-in-the-AArch64-Procedure-Call-Standard/Parameters-in-general-purpose-registers reports: QUOTE • X18 is the platform register and is reserved for the use of platform ABIs. This is an additional temporary register on platforms that don't assign a special meaning to it. END QUOTE So, special, yes. But I do not know what the "platform ABI" usage for it might be on FreeBSD. So, for the most part, this does not well-answer your question. Sorry. === Mark Millard marklmi at yahoo.com ( dsl-only.net went away in early 2018-Mar)home | help
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