Date: Wed, 06 Feb 2002 19:22:05 -0800 From: Peter Wemm <peter@wemm.org> To: Daniel Eischen <eischen@pcnet1.pcnet.com> Cc: Dan Eischen <eischen@vigrid.com>, arch@FreeBSD.ORG Subject: Re: getsetcontext system call Message-ID: <20020207032205.73E9239F1@overcee.wemm.org> In-Reply-To: <Pine.GSO.4.10.10202061700570.29032-100000@pcnet1.pcnet.com>
next in thread | previous in thread | raw e-mail | index | archive | help
Daniel Eischen wrote: > On Wed, 6 Feb 2002, Peter Wemm wrote: > > Dan Eischen wrote: > > > > > Diffs are at: > > > > > > http://people.freebsd.org/~deischen/ucontext/uc-sys.diffs > > > http://people.freebsd.org/~deischen/ucontext/uc-libc.diffs > > [..] > As to set_fpregs(), it looks like it wants to convert an x87 > FPU state to an SSE FPU state. The opposite seems to be the > case for fill_fpregs(). I'm not exactly sure how and why > fill_fpregs() and set_fpregs() are used. Since we make struct > fpreg large enough to hold either x87 or SSE FPU state, do we > even care about converting between the two different formats > any longer? I think we have to, because xmm state is a superset of the x87 state, and we need to not f*ck up defined interface to ptrace(PT_SETFPREGS etc and procfs where you supply an entire 'struct fpregs' to these calls. Imagine running a 4.x binary where it does a ptrace(PT_GETFPREGS, &fpregs); where '&fpregs' points to the traditional sized structure. You cant just change the size of it without doing things like assigning new syscall numbers to ptrace(2) etc and adding some workaround glue to procfs. We may need to do what linux does (SET/SET_FPXREGS) and maybe /proc/*/fpxregs. Ugh. Anyway, I dont see that you can just change 'struct fpregs' that easily. The union may have to be moved up higher for x86.. Cheers, -Peter -- Peter Wemm - peter@FreeBSD.org; peter@yahoo-inc.com; peter@netplex.com.au "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-arch" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20020207032205.73E9239F1>