Re: [Fwd: Re: [RFA 3/5] Prec: x86 segment register support: target]

[Hui Zhu <teawater at gmail dot com>]

On Fri, Apr 30, 2010 at 19:07, Hui Zhu <teawater@gmail.com> wrote:
> On Fri, Apr 30, 2010 at 17:33, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
>>> From: Hui Zhu <teawater@gmail.com>
>>> Date: Fri, 30 Apr 2010 14:29:09 +0800
>>>
>>> On Thu, Mar 25, 2010 at 10:14, Hui Zhu <teawater@gmail.com> wrote:
>>> > On Thu, Mar 25, 2010 at 02:44, Doug Evans <dje@google.com> wrote:
>>> >>
>>> >> On Mon, Mar 22, 2010 at 7:59 PM, Hui Zhu <teawater@gmail.com> wrote:
>>> >> > On Tue, Mar 23, 2010 at 02:47, Doug Evans <dje@google.com> wrote:
>>> >> >> On Mon, Mar 22, 2010 at 11:26 AM, Michael Snyder <msnyder@vmware.com> wrote:
>>> >> >>> I'd just like to point out that while all this sounds great,
>>> >> >>> it shouldn't be a prerequisite to the original task of just
>>> >> >>> getting prec to record the segments and offsets correctly.
>>> >> >>>
>>> >> >>> Maybe we should split these two tasks, so that Teawater can
>>> >> >>> go ahead and accomplish his.
>>> >> >>
>>> >> >> To the extent that they can be split, IWBN alright.
>>> >> >>
>>> >> >> I wonder if the interface is sufficient though (setting aside where to
>>> >> >> put it and how it will look).
>>> >> >> Any particular o/s might not provide sufficient hooks of course.
>>> >> >> linux's modify_ldt, AIUI, let's one change more than just foo_base.
>>> >> >> NativeClient http://code.google.com/p/nativeclient/ uses it, for example.
>>> >> >>
>>> >> >
>>> >> > Thanks Doug.
>>> >> >
>>> >> > I suggest we support segment base step by step.
>>> >> > When the OS that support it will show the xxx_base to user, the
>>> >> > unsupport OS will show nothing.
>>> >> >
>>> >> > What do you think about it?
>>> >>
>>> >> Is supporting segment base sufficient?
>>> >> Or do you also need to support, e.g., segment limit and flags too?
>>> >> There may be more, but they're the two that come to mind.
>>> >> [That's what I was referring to regarding whether the interface was sufficient.]
>>> >
>>> > Prec just need the base to get the insn memory operate address. ?Do
>>> > you think we need other message of segment?
>>> >
>>> > If need, do we need divide all message like eflags?
>>> >
>>> > Thanks,
>>> > Hui
>>> >
>>>
>>> Hi all,
>>>
>>> X86 looks stab now. ?Shall we wake up this patch?
>>
>> Thanks for the reminder.
>>
>> Let me first ask a question. ?What do people expect out of this? ?Do
>> they really want support for fully segmented code, or is it just for
>> small deviations like accessing per-thread storage through %fs/%gs?
>>
>
> Prec must know the each base of segment register.
>
> If you don't like it. ?What about the old way that I use? ?It doesn't
> add anything to reg list.
> But for the each way, we need add interface to the target part that
> prec can get the value.
>
> Thanks,
> Hui
>

Ping.

Thanks,
Hui