20 Jan
2006
20 Jan
'06
12:12 a.m.
Hi!
Alex Ionescu wrote:
Hi,
I'm going to answer generically, not point-by-point, since I don't have
much time, but I hope I can cover everything:
1) Those magic sizes were calculated in my head and I didn't have time
to make them into constants as I did many of them.
0x29C is the pre-defined value of NPX_FRAME_LENGTH + KTRAP_FRAME_LENGTH.
0x48 is the differerence in the KTRAP_FRAME between the registers that
we will skip. I could've done (KTRAP_FRAME_XXX - KTRAP_FRAME_YYY).
2) This is not a matter of driver compatibility. The fast system call
stub is a mostly hardware-defined entrypoint, handled by low-level
software logic. In implementing it, there are only 3 available sources
of information: Whatever minimal info the Intel manual gives, the Linux
sources, the Windows kernel binary. It is almost simply impossible to
"guess" how the stub should work. Filip tried to make it work more then
a year ago, and even he gave up (the AMD version), beacuse it is simply
too hard and confusing unless you have some available code to look at.
As such, my first and foremost source was the Linux source code. It
helped me understand how to setup the LSTAR MSR register, as well as the
other register values. Then, through several mailing list posts, I was
able to understand some bugs in the way ReactOS had its segments set up,
which caused problems in the code. Then, to understand the way Windows
chose between INT2E and SYSENTER, I found a document online written by a
person called Elicz, which described the stub and what it should do,
much in the same way people argued "clean-room reverse engineering" is
done. With this information, I was able to write more then 85% of the
stub. My next, and final remaining possible step, was to use IDA to look
at the Windows code. I used it as a learning tool, not as a copying
tool. It is hard to argue that what I did was "Reverse-engineering",
which, to my knowledge, implies taking something apart to re-create it,
since this usually implies converting the assembly code to functional C
code or otherwise. But I don't view as looking at assembly in order to
understand a low-level hardware interface as "reverse engineering". And
yes, as described above, it -was- my last choice. Additionally, the
parts which were supposedly "copied" are NOT part of the functional part
of the code. They are debug helpers, offering nothing else but
assertions in case of problems.
3) I find the idea of removing code that "Violates policy" ludicrous. No
one has the right to dermine if some piece of code violates policy or
not, especially if the author writing it denies it. Only a judge or
lawyer should be able to make that decision. Additionally, in this
specific case, what could be done? The code is in SVN and even if
rewritten it will 1) look the same, excpt "edx" would become "esi"
and
vice-versa 2) a judge would still argue that "hey, you had the previous
code in SVN for over a year, you've all been tainted and could've just
as easily looked at it". Furthermore, such attitude might start
devolving into a dangerous witchhunt. Don't like someone's code? Report
them and have it removed! This communist-era and fascist-era behaviour
deeply scares me and reminds me of a country and regime which I fled. I
do not want to see it happen, because it would slowly kill and rip apart
this project.
I hear a duck, Does anyone else hear a duck. Wow I do!
These monthly Alex-bashings are starting to tire me
very much and maybe
it's time I took an offensive position instead of a defensive one. I do
not want to start naming names, but many of our developers have already
violated our policy in different ways. If you actively start enforcing
it, then it will be my duty as an active developer to enforce it as
well, meaning that hiding any information I have concerning other
developers' violations would be considered as complicity, so I would be
legally bound to report them. In other words, this would mean that the
project would lose half of its developers.
I can start a formal investigation if you want?
I am sick of being treated as the black sheep and the
"example". This
stops here. I have always been put in the spotlight for almost any
action I took, and I've always taken steps to repair it. But these
public trials of guilt have passed a limit. Either start questionning
everyone and treating every developer the same, or stop using me as a tool.
Best regards,
Alex Ionescu
I would recommend everyone take a step back and think about this.
Please let us not wakeup that giant! (Not M$)
James