Messages in this thread | | | Date | Wed, 01 Feb 2006 21:56:44 -0800 (PST) | Subject | Re: [PATCH] compat: fix compat_sys_openat and friends | From | "David S. Miller" <> |
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From: Linus Torvalds <torvalds@osdl.org> Date: Wed, 1 Feb 2006 21:36:40 -0800 (PST)
> Wouldn't it be _much_ better to declare the argument as a "long", since > some architectures (alpha, for example) may assume that 32-bit arguments > have been _sign_extended, not zero-extended. > > Then, when the "compat_sys_xxxx()" function passes the "long" down to the > _real_ function (which takes an "int"), those architectures (and only > those architectures) that actually have assumptions about high bits will > have the compiler automatically do the right zero- or sign-extensions at > that call-site.
There is the convention that for the compat system calls all the args will be 32-bit zero extended by the platform syscall entry code before the C code is invoked. This topic used to come up a lot and finally we all decided that was the thing to do.
It's important (at least I think so :-) for all of this generic compat code to be able to have a well defined argument environment.
Anyways, I think that's how Stephen arrived at his patch. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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