Date: Mon, 30 Sep 2002 16:02:49 -0700 From: Peter Wemm <peter@wemm.org> To: Daniel Eischen <eischen@vigrid.com> Cc: current@freebsd.org Subject: Re: Longer term fix for sigreturn ABI breaking Message-ID: <20020930230249.E57AF2A7D6@canning.wemm.org> In-Reply-To: <3D98BF1A.4A58EE74@vigrid.com>
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Daniel Eischen wrote: > At the end is a potentially longer term fix for the ABI > breakage that was introduced when the i386 mcontext_t > was changed/enlarged. > - ret = set_fpcontext(td, &ucp->uc_mcontext); > - if (ret != 0) > - return (ret); > + /* > + * Intentionally ignore the error to keep binary > + * compatibility with applications that fiddle with > + * the FPU save area in the context. The kernel > + * now saves the FPU state in the context, but it > + * gets corrupted by those applications that try > + * to work around the kernel NOT saving it. > + */ > + (void)set_fpcontext(td, &ucp->uc_mcontext); Maybe we could have something like this instead? ret = set_fpcontext(td, &ucp->uc_mcontext); #if !defined(COMPAT_FREEBSD4) && !defined(COMPAT_43) if (ret != 0) return (ret); #endif ie: ignore the error only if we have to be compatable. Longer term, I was thining that we could/should do what sparc64 does, ie: libc provides the trampoline and it can then call the correct sigreturn syscall. That means we add a new sigreturn syscall each time we significantly break the sigreturn ABI (as in this case) and applications will be able to use the correct one. Paired with a new sigaction syscall which would specify the "new" context format we can then be future proof. Cheers, -Peter -- Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com "All of this is for nothing if we don't go to the stars" - JMS/B5 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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