Incomplete trace (due to high-speed SIM?)

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Min Xu mxu at sanjole.com
Thu Sep 5 08:37:40 UTC 2013


Hi Harald

Thank you for getting back to me so quickly.  I am using Emacs on an Ubuntu
netbook to do the edits, which likes to reformat sections as I move
(copy/paste section around) and I haven't figured out a command to undo
those changes.  It'd be nice if there is a .emacsrc or something that
automatically formats the code to the project standard? (presumably someone
has one? ..)

I started only wanted to make one change and submit (was initially the
req_ctx), but couldn't reliably verify it until the debugp was working
better without affecting the system, so the changes ballooned up to this
stage.  So I wanted to submit the changes before I change the code
further.  I will try limit the scope of changes in my future updates.

To your questions:

1) The numerical values of the RCTX_STATE are changed to facilitate the
choosing of the FIFO/double linked list of req_ctx to use.  An array of
FIFO, using the state to index into the array to get the FIFO is simplest.
When I looked how the reqctx_find / ... functions are used, I found all
callers use the constant name rather than any specific numeric value.

2) I will look at this tomorrow.  But I was under the impression on how the
lib_Atmel?? (sorry, can't access the source at the moment) was invoked to
install the irq handler, that the entry point to the interrupt would be
directly the function passed in.  I looked at the sysirq_handler.c?? more
closely than the other so I wasn't aware of the Cstartup.c file

Since I increased the req_ctx buffer size to 1kb each, most req_ctx that
are transferred to pc contain many many apdus but very often, the req_ctx
do not begin at the start of an apdu.  So I would like to have an offset (2
byte, since it could be > 256) to indicate the position of the first start
of an apdu.  After thinking about it more, I would also like to add a
sequence number into the header (making the header 8 bytes then?) to better
allow for detecting dropped req_ctx (if there are any..).  The offset would
be 8 for a req_ctx that starts with a new APDU, and would be 0 for an
req_ctx that only contains a middle or last fragment of an APDU.

I have already modified the host software to run on Windows (currently
using Windows 7 x64), so I will probably make those changes locally only to
help me detect any problem I might still be facing.

Again, thank you very much for getting back so quickly, and I appreciate
your product very much.

Best Regards

On Wed, Sep 4, 2013 at 9:31 PM, Harald Welte <laforge at gnumonks.org> wrote:

> Dear Min Xu,
>
> On Wed, Sep 04, 2013 at 07:47:46PM -1000, Min Xu wrote:
> > I made a bunch of changes that significantly improved my test scenario:
>
> I _really_ appreciate your excellent technical work.  However, I would
> like you to go the little extra effort it takes to 'properly' interact
> with community based Free Software projects, where there are rules like
>
> * only one feature / logical change per patch, resulting in a series
>   of incremental patches, each taking us one step further, each
>   rendering a compile-able and functional build after being applied.
> * no re-formatting of code (whitespace changes)
> * no patch for local changes like different compiler name in Makefile
> * stick to coding style of the project (tab-wide indent, ...) for
>   consistency
> * remove old/dead code rather than comment it out (RCTX_STATE_...)
> * avoid asm() statements whenever possible.  If you need them, please
>   wrap them in an inline C function with descriptive name.
>
> Some quesetions:
> * why did the numberic values of RCTX_STATE_* have t be changed rather
>   than amended by your new values, keeping the old ones as-is?
>
> * interrupt nesting _should_ have been active all the time, see
>   IRQ_Handler_Entry in Cstartup.S, where we first save SPSR and then
>   un-set the IRQ and FIQ bits _before_ branching to the interrupt
>   handler function:
>
>         /*- Enable Interrupt and Switch in Supervisor Mode */
>         msr     CPSR_c, #ARM_MODE_SVC
>
>   Where ARM_MODE_SVC is set to 0x13, i.e. without 0x40 or 0x80.
>
>   So if there's something wrong with the existing code, it should be
>   fixed there rather than two copies of inline-asm in the USART and USB
>   IRQ handler routines.
>
> So I do want to merge this very much, but I think it needs clean-up
> before it can be merged.  I don't expect to have much time for this in
> the next couple of weeks, so I would be happy if either you or somebody
> else on the list could work on this.
>
> Regarding your comment about changing the USB protocol:  This would lead
> to host / firmware version incompatibilities, and I'd like to avoid that
> if possible in any way.  We already have the simtrace_hdr.flags
> structure member, which contains things like SIMTRACE_FLAG_ATR.  I'm not
> sure if I understand your request fully, but why not simply add flags
> like:
>
> * First fragment of a fragmented APDU
> * More fragments to follow for this APDU
>
> This way a new APDU still has to start at the beginning of a USB
> transfer, but no changes to the simtrace_hdr are required.
>
>
> Thanks again,
>         Harald
>
>
> --
> - Harald Welte <laforge at gnumonks.org>
> http://laforge.gnumonks.org/
>
> ============================================================================
> "Privacy in residential applications is a desirable marketing option."
>                                                   (ETSI EN 300 175-7 Ch.
> A6)
>
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