gdbserver target description: info reg displays or not according to group presence ???

[Philippe Waroquiers]

Can I give any additional info for the below ?
Or help ?

Thanks

----- Original Message ----- 
From: "Philippe Waroquiers" <philippe.waroquiers@skynet.be>
To: "Daniel Jacobowitz" <dan@codesourcery.com>
Cc: <gdb@sourceware.org>
Sent: Thursday, August 12, 2010 9:08 PM
Subject: Re: gdbserver target description: info reg displays or not according to group presence ???


> Thanks for the reply/help.
> 
>> The problem with letting people specify random strings as group is
>> that GDB might grab those strings for a specific purpose in some
>> future version.  There's no registry or namespace.
> Is this really a problem ? 
> From what I understand, a group is (only?) useful to (in the future)
> allow to do 'info register <group>".
> If there is really some behaviour linked with a register group,
> then it is enough to specify something like:  
> "general", "all", "float", "vector", "save"  and group names starting 
> with "g" are standard group names reserved for gdb usage.
> 
>> Turns out there's a better fix too.  Does this work?
> It does not work according to the doc, but it provides
> a consistent behaviour. The behaviour is: 
>   if *no* group is given, then 'info reg' shows the registers.
> 
> With the patch, the behaviour is:
>   * if no group is specified, then a register belongs to the general group.
>   * the general group is shown by 'info reg'
>   * other (gdb known) groups are shown by 'info reg <group>'
>   * info all-reg shows all registers
>    * and in the future, we could have
>         info reg <non standard group name> shows the registers of this group.
> 
> Here is some more detailed info about the behaviour with the patch:
> 
> With the below (extract of) target description file:
> ...
>    <field name="VIP" start="20" end="20"/>
>    <field name="ID" start="21" end="21"/>
>  </flags>
> 
>  <reg name="eaxs1" bitsize="32" type="int32" group="float"/>
>  <reg name="ecxs1" bitsize="32" type="int32" group="groupecxs1"/>
>  <reg name="edxs1" bitsize="32" type="int32"/>
>  <reg name="ebxs1" bitsize="32" type="int32"/>
>  ...
> 
> info register gives
>  ...
>  es             0x0 0
>  fs             0x0 0
>  gs             0x7b0000 8060928
>  edxs1          0x0 0
>  ebxs1          0x0 0
>  esps1          0x0 0x0
>  ...
> 
> 
> So, specifying either a standard (float) or unknown (groupecxs1)
> group makes these registers not shown.
> But having no group at all (e.g. edxs1) still shows them.
> 
> maint print register-groups gives:
> ...
> orig_eax     49   49    308       4 long            save,restore,system
> eaxs1        50   50    312       4 int32_t         float,all,save,restore
> ecxs1        51   51    316       4 int32_t         all,save,restore
> edxs1        52   52    320       4 int32_t         general,all,save,restore
> ...
> 
> Philippe
>