[PATCH] doc: drop recommendation against bool in structures

[PATCH] doc: drop recommendation against bool in structures

[Maxime Leroy]

The coding style advised against bool in structures, citing space and
type-size concerns inherited from the Linux kernel. That does not match
DPDK practice: bool is already used in over 1400 structure fields across
the tree, including core APIs such as rte_flow. Drop the note so the
style guide reflects actual usage.

Signed-off-by: Maxime Leroy <maxime@leroys.fr>
---
 doc/guides/contributing/coding_style.rst | 9 ---------
 1 file changed, 9 deletions(-)

diff --git a/doc/guides/contributing/coding_style.rst b/doc/guides/contributing/coding_style.rst
index 976a1e1de3..11de3bb39a 100644
--- a/doc/guides/contributing/coding_style.rst
+++ b/doc/guides/contributing/coding_style.rst
@@ -313,15 +313,6 @@ Structure Declarations
 * Use of the structures should be by separate variable declarations and those declarations must be extern if they are declared in a header file.
 * Externally visible structure definitions should have the structure name prefixed by ``rte_`` to avoid namespace collisions.
 
-.. note::
-
-    Avoid using ``bool`` in structures because it wastes space and
-    the type size is unclear. A preferred use of
-    ``bool`` is mainly as a return type from functions that return true/false,
-    and maybe local variable functions.
-
-    Ref: `LKML <https://lkml.org/lkml/2017/11/21/384>`_
-
 Queues
 ~~~~~~
 
-- 
2.43.0

Re: [PATCH] doc: drop recommendation against bool in structures

[Bruce Richardson]

On Mon, Jul 20, 2026 at 01:46:02PM +0200, Maxime Leroy wrote:
> The coding style advised against bool in structures, citing space and
> type-size concerns inherited from the Linux kernel. That does not match
> DPDK practice: bool is already used in over 1400 structure fields across
> the tree, including core APIs such as rte_flow. Drop the note so the
> style guide reflects actual usage.
> 
> Signed-off-by: Maxime Leroy <maxime@leroys.fr>
> ---

Definite +1

Acked-by: Bruce Richardson <bruce.richardson@intel.com>

>  doc/guides/contributing/coding_style.rst | 9 ---------
>  1 file changed, 9 deletions(-)
> 
> diff --git a/doc/guides/contributing/coding_style.rst b/doc/guides/contributing/coding_style.rst
> index 976a1e1de3..11de3bb39a 100644
> --- a/doc/guides/contributing/coding_style.rst
> +++ b/doc/guides/contributing/coding_style.rst
> @@ -313,15 +313,6 @@ Structure Declarations
>  * Use of the structures should be by separate variable declarations and those declarations must be extern if they are declared in a header file.
>  * Externally visible structure definitions should have the structure name prefixed by ``rte_`` to avoid namespace collisions.
>  
> -.. note::
> -
> -    Avoid using ``bool`` in structures because it wastes space and
> -    the type size is unclear. A preferred use of
> -    ``bool`` is mainly as a return type from functions that return true/false,
> -    and maybe local variable functions.
> -
> -    Ref: `LKML <https://lkml.org/lkml/2017/11/21/384>`_
> -
>  Queues
>  ~~~~~~
>  
> -- 
> 2.43.0
> 

RE: [PATCH] doc: drop recommendation against bool in structures

[Morten Brørup]

> From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> Sent: Monday, 20 July 2026 14.13
> 
> On Mon, Jul 20, 2026 at 01:46:02PM +0200, Maxime Leroy wrote:
> > The coding style advised against bool in structures, citing space and
> > type-size concerns inherited from the Linux kernel. That does not
> match
> > DPDK practice: bool is already used in over 1400 structure fields
> across
> > the tree, including core APIs such as rte_flow. Drop the note so the
> > style guide reflects actual usage.

The note is still valid, although massively violated.
Could we paraphrase the note as an advice/recommendation, instead of completely removing it?
The intention is to make developers consider alternatives when adding a Boolean field to a structure.
Maybe it could be expanded with a few example alternatives:
uint8_t value, or
uintN_t value:1 (bitfield).

> >
> > Signed-off-by: Maxime Leroy <maxime@leroys.fr>
> > ---
> 
> Definite +1
> 
> Acked-by: Bruce Richardson <bruce.richardson@intel.com>
> 
> >  doc/guides/contributing/coding_style.rst | 9 ---------
> >  1 file changed, 9 deletions(-)
> >
> > diff --git a/doc/guides/contributing/coding_style.rst
> b/doc/guides/contributing/coding_style.rst
> > index 976a1e1de3..11de3bb39a 100644
> > --- a/doc/guides/contributing/coding_style.rst
> > +++ b/doc/guides/contributing/coding_style.rst
> > @@ -313,15 +313,6 @@ Structure Declarations
> >  * Use of the structures should be by separate variable declarations
> and those declarations must be extern if they are declared in a header
> file.
> >  * Externally visible structure definitions should have the structure
> name prefixed by ``rte_`` to avoid namespace collisions.
> >
> > -.. note::
> > -
> > -    Avoid using ``bool`` in structures because it wastes space and
> > -    the type size is unclear. A preferred use of
> > -    ``bool`` is mainly as a return type from functions that return
> true/false,
> > -    and maybe local variable functions.
> > -
> > -    Ref: `LKML <https://lkml.org/lkml/2017/11/21/384>`_
> > -
> >  Queues
> >  ~~~~~~
> >
> > --
> > 2.43.0
> >

Re: [PATCH] doc: drop recommendation against bool in structures

[Bruce Richardson]

On Mon, Jul 20, 2026 at 02:51:09PM +0200, Morten Brørup wrote:
> > From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> > Sent: Monday, 20 July 2026 14.13
> > 
> > On Mon, Jul 20, 2026 at 01:46:02PM +0200, Maxime Leroy wrote:
> > > The coding style advised against bool in structures, citing space and
> > > type-size concerns inherited from the Linux kernel. That does not
> > match
> > > DPDK practice: bool is already used in over 1400 structure fields
> > across
> > > the tree, including core APIs such as rte_flow. Drop the note so the
> > > style guide reflects actual usage.
> 
> The note is still valid, although massively violated.
> Could we paraphrase the note as an advice/recommendation, instead of completely removing it?
> The intention is to make developers consider alternatives when adding a Boolean field to a structure.
> Maybe it could be expanded with a few example alternatives:
> uint8_t value, or
> uintN_t value:1 (bitfield).
> 
I don't think we want those alternative approaches. If something is a
boolean value, then let's just store it as a bool and be done with it. If
we store it as an int type then we need comments documenting that it's
actually a flag. If it's a bit type, then the field becomes just that
little bit more awkward to manage - though still a good choice if the
struct is size-sensitive.

Because of this, I'd be in favour of just removing the text and then
letting the developer choose the best field type for the job. If bool is a
bad choice for a given situation, that should be caught in review.

/Bruce

RE: [PATCH] doc: drop recommendation against bool in structures

[Morten Brørup]

> From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> Sent: Monday, 20 July 2026 14.58
> 
> On Mon, Jul 20, 2026 at 02:51:09PM +0200, Morten Brørup wrote:
> > > From: Bruce Richardson [mailto:bruce.richardson@intel.com]
> > > Sent: Monday, 20 July 2026 14.13
> > >
> > > On Mon, Jul 20, 2026 at 01:46:02PM +0200, Maxime Leroy wrote:
> > > > The coding style advised against bool in structures, citing space
> and
> > > > type-size concerns inherited from the Linux kernel. That does not
> > > match
> > > > DPDK practice: bool is already used in over 1400 structure fields
> > > across
> > > > the tree, including core APIs such as rte_flow. Drop the note so
> the
> > > > style guide reflects actual usage.
> >
> > The note is still valid, although massively violated.
> > Could we paraphrase the note as an advice/recommendation, instead of
> completely removing it?
> > The intention is to make developers consider alternatives when adding
> a Boolean field to a structure.
> > Maybe it could be expanded with a few example alternatives:
> > uint8_t value, or
> > uintN_t value:1 (bitfield).
> >
> I don't think we want those alternative approaches. If something is a
> boolean value, then let's just store it as a bool and be done with it.
> If
> we store it as an int type then we need comments documenting that it's
> actually a flag. If it's a bit type, then the field becomes just that
> little bit more awkward to manage - though still a good choice if the
> struct is size-sensitive.
> 
> Because of this, I'd be in favour of just removing the text and then
> letting the developer choose the best field type for the job. If bool
> is a
> bad choice for a given situation, that should be caught in review.
> 
> /Bruce

OK, I'll buy that.

Acked-by: Morten Brørup <mb@smartsharesystems.com>