Date: Tue, 23 Jun 2015 00:35:12 +0100 From: Andrew Turner <andrew@fubar.geek.nz> To: <freebsd-arm@freebsd.org> Subject: HEADS UP: Changing the arm64 userland entry ABI Message-ID: <20150623003512.0e2c03b6@bender.Home>
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If you don't use FreeBSD/arm64 you can stop reading now. I'm changing the ABI for how the kernel provides the stack and the pointer to the arguments. Currently both are provided through the stack pointer, however this means the stack may be misaligned. I'm changing this to have the stack pointer be correctly aligned, and have a register (x0) point to the arguments. This will mean a new kernel with old userland, or vice versa will fail. To allow for there to be a transition, I've updated the userland side to handle either the current or new ABI, and expect to update the kernel in a week or two. When the kernel is updated only a userland built from r284707 [1] or later will work. There will also need to be similar changes made to qemu usermode to support this. The good news from this is this fixes the crash seen with clang, and I have managed to get buildkernel to complete. Andrew [1] https://svnweb.freebsd.org/changeset/base/284707
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