* Register View bitfields support
@ 2024-02-09 12:56 Robert Pîrvu
2024-02-16 12:00 ` Guinevere Larsen
0 siblings, 1 reply; 3+ messages in thread
From: Robert Pîrvu @ 2024-02-09 12:56 UTC (permalink / raw)
To: gdb; +Cc: Sebastian Perta, Mark Goodchild
Hello,
I am a cdt developer and I'm working on a new functionality for
Eclipse's Register View.
The current implementation of the Register View does not allow the
display of individual fields of a register with bitfields. This
functionality is only available in the Expression view by creating a new
expression using the “$” and the name of the register.
Register view has a grouping functionality that allows us to create
custom groups of registers, those groups can be expanded and collapsed
to show/hide the register in the said group. The same functionality of
expanding and collapsing can be added to a register with bitfield.
The implementation of this would require the modification of the
-data-list-register-values MI Command to include a list of registers’s
bitfields.
And the introduction of a new MI Command
-data-list-register-bitfields-name, is also needed to retrieve the names
of the bitfields.
The modified -data-list-register-values would have the following format:
Command: -data-list-register-values [ --skip-unavailable ] fmt [ ( regno
)*]
Respone:
^done,register-values=[{number="0",value="0”,bitfields=“{value=0,
value=0}"}, {number="1",value="{0}”,bitfields=“{[]},...]
Format of the response: [{number="0",value="0”,bitfields=“{[value=0],
[value=0]}"}]
The --skip-unavailable option indicates that only the available
registers are to be returned.
The regno option indicates that only the specified register needs to be
returned. If no register is specified then all registers will be
returned.
The fmt indicates the format according to which the registers' contents
are to be returned. Allowed formats for fmt are:
Hexadecimal - x
Octal - o
Binary - t
Decimal - d
Raw - r
Natural - N
If a register doesn't have bitfields, then the bitfields list will be
empty or it can be not included in the response.
The new MI Command will have the following format:
Command: -data-list-register-bitfield-name [ ( regno )+ ]
Response: ^done,register-bitfield-names=[{name="reg0", bitfields =["C",
"M"]},{name="reg1", bitfields =["A", "B"]}, ...]
The regno option indicates that only the specified register needs to be
returned. If no register is specified then all registers will be
returned.
If the register doesn't have bitfields, then the bitfields list will be
empty or not included in the response.
Any feedback regarding this feature is greatly appreciated and we are
open to contribute to its implementation.
Best Regards,
Robert.
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Register View bitfields support
2024-02-09 12:56 Register View bitfields support Robert Pîrvu
@ 2024-02-16 12:00 ` Guinevere Larsen
2024-03-05 9:57 ` Robert Pîrvu
0 siblings, 1 reply; 3+ messages in thread
From: Guinevere Larsen @ 2024-02-16 12:00 UTC (permalink / raw)
To: Robert Pîrvu, gdb; +Cc: Sebastian Perta, Mark Goodchild
On 09/02/2024 13:56, Robert Pîrvu via Gdb wrote:
> Hello,
>
> I am a cdt developer and I'm working on a new functionality for
> Eclipse's Register View.
Hi!
I'm replying to this mostly so you're not left out to dry, since I'm not
too familiar with the MI interpreter and I never seen anything like this
in the CLI interpreter. That said, I do have a few thoughts left inline
>
> The current implementation of the Register View does not allow the
> display of individual fields of a register with bitfields. This
> functionality is only available in the Expression view by creating a
> new expression using the “$” and the name of the register.
> Register view has a grouping functionality that allows us to create
> custom groups of registers, those groups can be expanded and collapsed
> to show/hide the register in the said group. The same functionality of
> expanding and collapsing can be added to a register with bitfield.
My first question is: Does GDB already know of these bitfields? I am not
sure if it does or not from your description of using Expression View.
If we already know, having a convenient way to access them sounds like a
good idea.
If we don't, are they architecture specific? Is the expectation that
we'd keep that information up to date? Or is this something that should
(or could) be user-defined? If the latter, the implementation should
probably come with a way to define them.
Sorry if these questions are very basic, this is pretty far from the
bits I work on
>
> The implementation of this would require the modification of the
> -data-list-register-values MI Command to include a list of registers’s
> bitfields.
> And the introduction of a new MI Command
> -data-list-register-bitfields-name, is also needed to retrieve the
> names of the bitfields.
>
> The modified -data-list-register-values would have the following format:
>
> Command: -data-list-register-values [ --skip-unavailable ] fmt [ (
> regno )*]
> Respone:
> ^done,register-values=[{number="0",value="0”,bitfields=“{value=0,
> value=0}"}, {number="1",value="{0}”,bitfields=“{[]},...]
> Format of the response: [{number="0",value="0”,bitfields=“{[value=0],
> [value=0]}"}]
>
> The --skip-unavailable option indicates that only the available
> registers are to be returned.
> The regno option indicates that only the specified register needs to
> be returned. If no register is specified then all registers will be
> returned.
> The fmt indicates the format according to which the registers'
> contents are to be returned. Allowed formats for fmt are:
>
> Hexadecimal - x
> Octal - o
> Binary - t
> Decimal - d
> Raw - r
> Natural - N
>
> If a register doesn't have bitfields, then the bitfields list will be
> empty or it can be not included in the response.
I think this is a complicated change. I'm not sure how strict we are
with output consistency, but I think we have to be pretty consistent to
not break every user of the MI protocol, so adding a new field in this
return doesn't sound like a great idea to me.
I would suggest adding a new option, --with-bitfields for example, which
has this output, and leave the default response with the same format.
>
> The new MI Command will have the following format:
>
> Command: -data-list-register-bitfield-name [ ( regno )+ ]
> Response: ^done,register-bitfield-names=[{name="reg0", bitfields
> =["C", "M"]},{name="reg1", bitfields =["A", "B"]}, ...]
>
> The regno option indicates that only the specified register needs to
> be returned. If no register is specified then all registers will be
> returned.
>
> If the register doesn't have bitfields, then the bitfields list will
> be empty or not included in the response.
When would registers not be included? From the previous paragraph it
sounds like they'd always be included, and having empty lists make sense.
I don't have any strong opinions on which option is better, just
commenting on the current explanation. Either way, this can be worked
out when the implementation itself is being discussed in the patches
that add it.
>
> Any feedback regarding this feature is greatly appreciated and we are
> open to contribute to its implementation.
I think this is a cool idea, regardless if these bitfields are
arch-defined or user-defined. If you show up with patches with an
implementation for this, I'll be happy to do my best in reviewing them
(though I can't approve them for merging), otherwise I think the best
way to go about it is opening a feature request (called Request For
Enhancement, RFE) on our bug tracker (https://sourceware.org/bugzilla/).
You can open the bug yourself or I can open for you if you have troubles
with the account creation process.
--
Cheers,
Guinevere Larsen
She/Her/Hers
>
> Best Regards,
> Robert.
>
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: Register View bitfields support
2024-02-16 12:00 ` Guinevere Larsen
@ 2024-03-05 9:57 ` Robert Pîrvu
0 siblings, 0 replies; 3+ messages in thread
From: Robert Pîrvu @ 2024-03-05 9:57 UTC (permalink / raw)
To: gdb; +Cc: Guinevere Larsen
On 2024-02-16 14:00, Guinevere Larsen wrote:
> On 09/02/2024 13:56, Robert Pîrvu via Gdb wrote:
>> Hello,
>>
>> I am a cdt developer and I'm working on a new functionality for
>> Eclipse's Register View.
>
> Hi!
>
> I'm replying to this mostly so you're not left out to dry, since I'm
> not too familiar with the MI interpreter and I never seen anything
> like this in the CLI interpreter. That said, I do have a few thoughts
> left inline
>
Hello Guinevere, thank you for the reply :)
>>
>> The current implementation of the Register View does not allow the
>> display of individual fields of a register with bitfields. This
>> functionality is only available in the Expression view by creating a
>> new expression using the “$” and the name of the register.
>> Register view has a grouping functionality that allows us to create
>> custom groups of registers, those groups can be expanded and collapsed
>> to show/hide the register in the said group. The same functionality of
>> expanding and collapsing can be added to a register with bitfield.
>
> My first question is: Does GDB already know of these bitfields? I am
> not sure if it does or not from your description of using Expression
> View. If we already know, having a convenient way to access them
> sounds like a good idea.
>
> If we don't, are they architecture specific? Is the expectation that
> we'd keep that information up to date? Or is this something that
> should (or could) be user-defined? If the latter, the implementation
> should probably come with a way to define them.
>
> Sorry if these questions are very basic, this is pretty far from the
> bits I work on
>
As far as I am aware, at the start of the debugging session, GDB already
has data about the registers such as names, positions, and values. With
the current format of the -data-list-register-values MI Command,
bitfields are returned together with the register's value under the
following format: value={Register Value In Specified Format,[List of
Bitfields Names]}.
>>
>> The implementation of this would require the modification of the
>> -data-list-register-values MI Command to include a list of registers’s
>> bitfields.
>> And the introduction of a new MI Command
>> -data-list-register-bitfields-name, is also needed to retrieve the
>> names of the bitfields.
>>
>> The modified -data-list-register-values would have the following
>> format:
>>
>> Command: -data-list-register-values [ --skip-unavailable ] fmt [ (
>> regno )*]
>> Respone:
>> ^done,register-values=[{number="0",value="0”,bitfields=“{value=0,
>> value=0}"}, {number="1",value="{0}”,bitfields=“{[]},...]
>> Format of the response: [{number="0",value="0”,bitfields=“{[value=0],
>> [value=0]}"}]
>>
>> The --skip-unavailable option indicates that only the available
>> registers are to be returned.
>> The regno option indicates that only the specified register needs to
>> be returned. If no register is specified then all registers will be
>> returned.
>> The fmt indicates the format according to which the registers'
>> contents are to be returned. Allowed formats for fmt are:
>>
>> Hexadecimal - x
>> Octal - o
>> Binary - t
>> Decimal - d
>> Raw - r
>> Natural - N
>>
>> If a register doesn't have bitfields, then the bitfields list will be
>> empty or it can be not included in the response.
>
> I think this is a complicated change. I'm not sure how strict we are
> with output consistency, but I think we have to be pretty consistent
> to not break every user of the MI protocol, so adding a new field in
> this return doesn't sound like a great idea to me.
>
> I would suggest adding a new option, --with-bitfields for example,
> which has this output, and leave the default response with the same
> format.
This is a good idea, I wasn't aware it was possible to change the output
format in this way.
>
>>
>> The new MI Command will have the following format:
>>
>> Command: -data-list-register-bitfield-name [ ( regno )+ ]
>> Response: ^done,register-bitfield-names=[{name="reg0", bitfields
>> =["C", "M"]},{name="reg1", bitfields =["A", "B"]}, ...]
>>
>> The regno option indicates that only the specified register needs to
>> be returned. If no register is specified then all registers will be
>> returned.
>>
>> If the register doesn't have bitfields, then the bitfields list will
>> be empty or not included in the response.
>
> When would registers not be included? From the previous paragraph it
> sounds like they'd always be included, and having empty lists make
> sense.
You're right having empty lists makes more sense than not returning
anything at all. And I don't think there will be any case in which a
register would not be returned.
>
> I don't have any strong opinions on which option is better, just
> commenting on the current explanation. Either way, this can be worked
> out when the implementation itself is being discussed in the patches
> that add it.
>
Register View uses two MI Commands to populate the view with registers.
One command which returns the names of the registers, and another one
which returns the positions and values of the registers. I wanted to
have a bit of consistency with the commands and that is why I proposed
to have something similar, one command to return the names of bitfields
and one for the values. And it will be a lot easier for this to work
with the existing parsers used by the Register View.
>>
>> Any feedback regarding this feature is greatly appreciated and we are
>> open to contribute to its implementation.
>
> I think this is a cool idea, regardless if these bitfields are
> arch-defined or user-defined. If you show up with patches with an
> implementation for this, I'll be happy to do my best in reviewing them
> (though I can't approve them for merging), otherwise I think the best
> way to go about it is opening a feature request (called Request For
> Enhancement, RFE) on our bug tracker
> (https://sourceware.org/bugzilla/). You can open the bug yourself or I
> can open for you if you have troubles with the account creation
> process.
Thank you again for your feedback. As you advised me I opened a Feature
Request on the Bug Tracker:
https://sourceware.org/bugzilla/show_bug.cgi?id=31448 including your
suggestion with the --with-bitfields option for the
-data-list-register-values MI Command.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2024-02-16 12:00 ` Guinevere Larsen
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