Date: Wed, 11 Feb 2015 11:57:59 -0800 From: "H.J. Lu" <hjl.tools@...il.com> To: Rich Felker <dalias@...c.org> Cc: Catalin Marinas <catalin.marinas@....com>, Andrew Pinski <apinski@...ium.com>, "linux-arm-kernel@...ts.infradead.org" <linux-arm-kernel@...ts.infradead.org>, LKML <linux-kernel@...r.kernel.org>, Andrew Pinski <pinskia@...il.com>, musl@...ts.openwall.com, GNU C Library <libc-alpha@...rceware.org> Subject: Re: [PATCHv3 00/24] ILP32 support in ARM64 >> > trivially satisfied if you consider x32 and x86_64 separate >> > compilation environments, but it's not related to the core issue: that >> > the definition of timespec violates core (not obscure) requirements of >> > both POSIX and C11. At the time you were probably unaware of the C11 >> > requirement. Note that it's a LOT harder to effect change in the C >> > standard, so even if the Austin Group would be amenable to changing >> > the requirement for timespec to allow something like nseconds_t, >> > getting WG14 to make this change to work around a Linux/glibc mistake >> > does not sound practical. >> >> That is very unfortunate. I consider it is too late for x32 to change. > > Why? It's hardly an incompatible ABI change, as long as the > kernel/libc fills the upper bits (for old programs that read them > based on the old headers) when structs are read from the kernel to the > application, and ignores the upper bits (potentially set or left > uninitialized by the application) when strings are passed from > userspace to the kernel. Newly built apps using the struct definition > with 32-bit tv_nsec would need new libc to ensure that the high bits > aren't interpreted, but this could be handled by symbol versioning. > We have considered this option. But since kernel wouldn't change tv_nsec/tv_usec handling just for x32, it wasn't selected. -- H.J.
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