mbox series

[v4,00/24] Remove COMMAND_LINE_SIZE from uapi

Message ID 20230302093539.372962-1-alexghiti@rivosinc.com (mailing list archive)
Headers show
Series Remove COMMAND_LINE_SIZE from uapi | expand

Message

Alexandre Ghiti March 2, 2023, 9:35 a.m. UTC
This all came up in the context of increasing COMMAND_LINE_SIZE in the
RISC-V port.  In theory that's a UABI break, as COMMAND_LINE_SIZE is the
maximum length of /proc/cmdline and userspace could staticly rely on
that to be correct.

Usually I wouldn't mess around with changing this sort of thing, but
PowerPC increased it with a5980d064fe2 ("powerpc: Bump COMMAND_LINE_SIZE
to 2048").  There are also a handful of examples of COMMAND_LINE_SIZE
increasing, but they're from before the UAPI split so I'm not quite sure
what that means: e5a6a1c90948 ("powerpc: derive COMMAND_LINE_SIZE from
asm-generic"), 684d2fd48e71 ("[S390] kernel: Append scpdata to kernel
boot command line"), 22242681cff5 ("MIPS: Extend COMMAND_LINE_SIZE"),
and 2b74b85693c7 ("sh: Derive COMMAND_LINE_SIZE from
asm-generic/setup.h.").

It seems to me like COMMAND_LINE_SIZE really just shouldn't have been
part of the uapi to begin with, and userspace should be able to handle
/proc/cmdline of whatever length it turns out to be.  I don't see any
references to COMMAND_LINE_SIZE anywhere but Linux via a quick Google
search, but that's not really enough to consider it unused on my end.

This issue was already considered in s390 and they reached the same
conclusion in commit 622021cd6c56 ("s390: make command line
configurable").

The feedback on the v1 seemed to indicate that COMMAND_LINE_SIZE really
shouldn't be part of uapi, so this now touches all the ports.  I've
tried to split this all out and leave it bisectable, but I haven't
tested it all that aggressively.

Changes since v3 <https://lore.kernel.org/all/20230214074925.228106-1-alexghiti@rivosinc.com/>:
* Added RB/AB
* Added a mention to commit 622021cd6c56 ("s390: make command line
  configurable") in the cover letter

Changes since v2 <https://lore.kernel.org/all/20221211061358.28035-1-palmer@rivosinc.com/>:
* Fix sh, csky and ia64 builds, as reported by kernel test robot

Changes since v1 <https://lore.kernel.org/all/20210423025545.313965-1-palmer@dabbelt.com/>:
* Touches every arch.

base-commit-tag: next-20230207

Palmer Dabbelt (24):
  alpha: Remove COMMAND_LINE_SIZE from uapi
  arm64: Remove COMMAND_LINE_SIZE from uapi
  arm: Remove COMMAND_LINE_SIZE from uapi
  ia64: Remove COMMAND_LINE_SIZE from uapi
  m68k: Remove COMMAND_LINE_SIZE from uapi
  microblaze: Remove COMMAND_LINE_SIZE from uapi
  mips: Remove COMMAND_LINE_SIZE from uapi
  parisc: Remove COMMAND_LINE_SIZE from uapi
  powerpc: Remove COMMAND_LINE_SIZE from uapi
  sparc: Remove COMMAND_LINE_SIZE from uapi
  xtensa: Remove COMMAND_LINE_SIZE from uapi
  asm-generic: Remove COMMAND_LINE_SIZE from uapi
  alpha: Remove empty <uapi/asm/setup.h>
  arc: Remove empty <uapi/asm/setup.h>
  m68k: Remove empty <uapi/asm/setup.h>
  arm64: Remove empty <uapi/asm/setup.h>
  microblaze: Remove empty <uapi/asm/setup.h>
  sparc: Remove empty <uapi/asm/setup.h>
  parisc: Remove empty <uapi/asm/setup.h>
  x86: Remove empty <uapi/asm/setup.h>
  xtensa: Remove empty <uapi/asm/setup.h>
  powerpc: Remove empty <uapi/asm/setup.h>
  mips: Remove empty <uapi/asm/setup.h>
  s390: Remove empty <uapi/asm/setup.h>

 .../admin-guide/kernel-parameters.rst         |  2 +-
 arch/alpha/include/asm/setup.h                |  4 +--
 arch/alpha/include/uapi/asm/setup.h           |  7 -----
 arch/arc/include/asm/setup.h                  |  1 -
 arch/arc/include/uapi/asm/setup.h             |  6 -----
 arch/arm/include/asm/setup.h                  |  1 +
 arch/arm/include/uapi/asm/setup.h             |  2 --
 arch/arm64/include/asm/setup.h                |  3 ++-
 arch/arm64/include/uapi/asm/setup.h           | 27 -------------------
 arch/ia64/include/asm/setup.h                 | 10 +++++++
 arch/ia64/include/uapi/asm/setup.h            |  6 ++---
 arch/loongarch/include/asm/setup.h            |  2 +-
 arch/m68k/include/asm/setup.h                 |  3 +--
 arch/m68k/include/uapi/asm/setup.h            | 17 ------------
 arch/microblaze/include/asm/setup.h           |  2 +-
 arch/microblaze/include/uapi/asm/setup.h      | 20 --------------
 arch/mips/include/asm/setup.h                 |  3 ++-
 arch/mips/include/uapi/asm/setup.h            |  8 ------
 arch/parisc/include/{uapi => }/asm/setup.h    |  0
 arch/powerpc/include/asm/setup.h              |  2 +-
 arch/powerpc/include/uapi/asm/setup.h         |  7 -----
 arch/s390/include/asm/setup.h                 |  1 -
 arch/s390/include/uapi/asm/setup.h            |  1 -
 arch/sh/include/asm/setup.h                   |  2 +-
 arch/sparc/include/asm/setup.h                |  6 ++++-
 arch/sparc/include/uapi/asm/setup.h           | 16 -----------
 arch/x86/include/asm/setup.h                  |  2 --
 arch/x86/include/uapi/asm/setup.h             |  1 -
 arch/xtensa/include/{uapi => }/asm/setup.h    |  0
 include/asm-generic/Kbuild                    |  1 +
 include/{uapi => }/asm-generic/setup.h        |  0
 include/uapi/asm-generic/Kbuild               |  1 -
 32 files changed, 31 insertions(+), 133 deletions(-)
 delete mode 100644 arch/alpha/include/uapi/asm/setup.h
 delete mode 100644 arch/arc/include/uapi/asm/setup.h
 delete mode 100644 arch/arm64/include/uapi/asm/setup.h
 create mode 100644 arch/ia64/include/asm/setup.h
 delete mode 100644 arch/m68k/include/uapi/asm/setup.h
 delete mode 100644 arch/microblaze/include/uapi/asm/setup.h
 delete mode 100644 arch/mips/include/uapi/asm/setup.h
 rename arch/parisc/include/{uapi => }/asm/setup.h (100%)
 delete mode 100644 arch/powerpc/include/uapi/asm/setup.h
 delete mode 100644 arch/s390/include/uapi/asm/setup.h
 delete mode 100644 arch/sparc/include/uapi/asm/setup.h
 delete mode 100644 arch/x86/include/uapi/asm/setup.h
 rename arch/xtensa/include/{uapi => }/asm/setup.h (100%)
 rename include/{uapi => }/asm-generic/setup.h (100%)

Comments

Geert Uytterhoeven March 2, 2023, 9:47 a.m. UTC | #1
Hi Alex,

On Thu, Mar 2, 2023 at 10:35 AM Alexandre Ghiti <alexghiti@rivosinc.com> wrote:
> This all came up in the context of increasing COMMAND_LINE_SIZE in the
> RISC-V port.  In theory that's a UABI break, as COMMAND_LINE_SIZE is the
> maximum length of /proc/cmdline and userspace could staticly rely on
> that to be correct.
>
> Usually I wouldn't mess around with changing this sort of thing, but
> PowerPC increased it with a5980d064fe2 ("powerpc: Bump COMMAND_LINE_SIZE
> to 2048").  There are also a handful of examples of COMMAND_LINE_SIZE
> increasing, but they're from before the UAPI split so I'm not quite sure
> what that means: e5a6a1c90948 ("powerpc: derive COMMAND_LINE_SIZE from
> asm-generic"), 684d2fd48e71 ("[S390] kernel: Append scpdata to kernel
> boot command line"), 22242681cff5 ("MIPS: Extend COMMAND_LINE_SIZE"),
> and 2b74b85693c7 ("sh: Derive COMMAND_LINE_SIZE from
> asm-generic/setup.h.").
>
> It seems to me like COMMAND_LINE_SIZE really just shouldn't have been
> part of the uapi to begin with, and userspace should be able to handle
> /proc/cmdline of whatever length it turns out to be.  I don't see any
> references to COMMAND_LINE_SIZE anywhere but Linux via a quick Google
> search, but that's not really enough to consider it unused on my end.
>
> This issue was already considered in s390 and they reached the same
> conclusion in commit 622021cd6c56 ("s390: make command line
> configurable").
>
> The feedback on the v1 seemed to indicate that COMMAND_LINE_SIZE really
> shouldn't be part of uapi, so this now touches all the ports.  I've
> tried to split this all out and leave it bisectable, but I haven't
> tested it all that aggressively.
>
> Changes since v3 <https://lore.kernel.org/all/20230214074925.228106-1-alexghiti@rivosinc.com/>:
> * Added RB/AB
> * Added a mention to commit 622021cd6c56 ("s390: make command line
>   configurable") in the cover letter

Thanks for the update!

 Apparently you forgot to add your own SoB?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
Alexandre Ghiti March 2, 2023, 10:06 a.m. UTC | #2
Hi Arnd,

On 3/2/23 10:35, Alexandre Ghiti wrote:
> This all came up in the context of increasing COMMAND_LINE_SIZE in the
> RISC-V port.  In theory that's a UABI break, as COMMAND_LINE_SIZE is the
> maximum length of /proc/cmdline and userspace could staticly rely on
> that to be correct.
>
> Usually I wouldn't mess around with changing this sort of thing, but
> PowerPC increased it with a5980d064fe2 ("powerpc: Bump COMMAND_LINE_SIZE
> to 2048").  There are also a handful of examples of COMMAND_LINE_SIZE
> increasing, but they're from before the UAPI split so I'm not quite sure
> what that means: e5a6a1c90948 ("powerpc: derive COMMAND_LINE_SIZE from
> asm-generic"), 684d2fd48e71 ("[S390] kernel: Append scpdata to kernel
> boot command line"), 22242681cff5 ("MIPS: Extend COMMAND_LINE_SIZE"),
> and 2b74b85693c7 ("sh: Derive COMMAND_LINE_SIZE from
> asm-generic/setup.h.").
>
> It seems to me like COMMAND_LINE_SIZE really just shouldn't have been
> part of the uapi to begin with, and userspace should be able to handle
> /proc/cmdline of whatever length it turns out to be.  I don't see any
> references to COMMAND_LINE_SIZE anywhere but Linux via a quick Google
> search, but that's not really enough to consider it unused on my end.
>
> This issue was already considered in s390 and they reached the same
> conclusion in commit 622021cd6c56 ("s390: make command line
> configurable").
>
> The feedback on the v1 seemed to indicate that COMMAND_LINE_SIZE really
> shouldn't be part of uapi, so this now touches all the ports.  I've
> tried to split this all out and leave it bisectable, but I haven't
> tested it all that aggressively.
>
> Changes since v3 <https://lore.kernel.org/all/20230214074925.228106-1-alexghiti@rivosinc.com/>:
> * Added RB/AB
> * Added a mention to commit 622021cd6c56 ("s390: make command line
>    configurable") in the cover letter
>
> Changes since v2 <https://lore.kernel.org/all/20221211061358.28035-1-palmer@rivosinc.com/>:
> * Fix sh, csky and ia64 builds, as reported by kernel test robot
>
> Changes since v1 <https://lore.kernel.org/all/20210423025545.313965-1-palmer@dabbelt.com/>:
> * Touches every arch.
>
> base-commit-tag: next-20230207
>
> Palmer Dabbelt (24):
>    alpha: Remove COMMAND_LINE_SIZE from uapi
>    arm64: Remove COMMAND_LINE_SIZE from uapi
>    arm: Remove COMMAND_LINE_SIZE from uapi
>    ia64: Remove COMMAND_LINE_SIZE from uapi
>    m68k: Remove COMMAND_LINE_SIZE from uapi
>    microblaze: Remove COMMAND_LINE_SIZE from uapi
>    mips: Remove COMMAND_LINE_SIZE from uapi
>    parisc: Remove COMMAND_LINE_SIZE from uapi
>    powerpc: Remove COMMAND_LINE_SIZE from uapi
>    sparc: Remove COMMAND_LINE_SIZE from uapi
>    xtensa: Remove COMMAND_LINE_SIZE from uapi
>    asm-generic: Remove COMMAND_LINE_SIZE from uapi
>    alpha: Remove empty <uapi/asm/setup.h>
>    arc: Remove empty <uapi/asm/setup.h>
>    m68k: Remove empty <uapi/asm/setup.h>
>    arm64: Remove empty <uapi/asm/setup.h>
>    microblaze: Remove empty <uapi/asm/setup.h>
>    sparc: Remove empty <uapi/asm/setup.h>
>    parisc: Remove empty <uapi/asm/setup.h>
>    x86: Remove empty <uapi/asm/setup.h>
>    xtensa: Remove empty <uapi/asm/setup.h>
>    powerpc: Remove empty <uapi/asm/setup.h>
>    mips: Remove empty <uapi/asm/setup.h>
>    s390: Remove empty <uapi/asm/setup.h>
>
>   .../admin-guide/kernel-parameters.rst         |  2 +-
>   arch/alpha/include/asm/setup.h                |  4 +--
>   arch/alpha/include/uapi/asm/setup.h           |  7 -----
>   arch/arc/include/asm/setup.h                  |  1 -
>   arch/arc/include/uapi/asm/setup.h             |  6 -----
>   arch/arm/include/asm/setup.h                  |  1 +
>   arch/arm/include/uapi/asm/setup.h             |  2 --
>   arch/arm64/include/asm/setup.h                |  3 ++-
>   arch/arm64/include/uapi/asm/setup.h           | 27 -------------------
>   arch/ia64/include/asm/setup.h                 | 10 +++++++
>   arch/ia64/include/uapi/asm/setup.h            |  6 ++---
>   arch/loongarch/include/asm/setup.h            |  2 +-
>   arch/m68k/include/asm/setup.h                 |  3 +--
>   arch/m68k/include/uapi/asm/setup.h            | 17 ------------
>   arch/microblaze/include/asm/setup.h           |  2 +-
>   arch/microblaze/include/uapi/asm/setup.h      | 20 --------------
>   arch/mips/include/asm/setup.h                 |  3 ++-
>   arch/mips/include/uapi/asm/setup.h            |  8 ------
>   arch/parisc/include/{uapi => }/asm/setup.h    |  0
>   arch/powerpc/include/asm/setup.h              |  2 +-
>   arch/powerpc/include/uapi/asm/setup.h         |  7 -----
>   arch/s390/include/asm/setup.h                 |  1 -
>   arch/s390/include/uapi/asm/setup.h            |  1 -
>   arch/sh/include/asm/setup.h                   |  2 +-
>   arch/sparc/include/asm/setup.h                |  6 ++++-
>   arch/sparc/include/uapi/asm/setup.h           | 16 -----------
>   arch/x86/include/asm/setup.h                  |  2 --
>   arch/x86/include/uapi/asm/setup.h             |  1 -
>   arch/xtensa/include/{uapi => }/asm/setup.h    |  0
>   include/asm-generic/Kbuild                    |  1 +
>   include/{uapi => }/asm-generic/setup.h        |  0
>   include/uapi/asm-generic/Kbuild               |  1 -
>   32 files changed, 31 insertions(+), 133 deletions(-)
>   delete mode 100644 arch/alpha/include/uapi/asm/setup.h
>   delete mode 100644 arch/arc/include/uapi/asm/setup.h
>   delete mode 100644 arch/arm64/include/uapi/asm/setup.h
>   create mode 100644 arch/ia64/include/asm/setup.h
>   delete mode 100644 arch/m68k/include/uapi/asm/setup.h
>   delete mode 100644 arch/microblaze/include/uapi/asm/setup.h
>   delete mode 100644 arch/mips/include/uapi/asm/setup.h
>   rename arch/parisc/include/{uapi => }/asm/setup.h (100%)
>   delete mode 100644 arch/powerpc/include/uapi/asm/setup.h
>   delete mode 100644 arch/s390/include/uapi/asm/setup.h
>   delete mode 100644 arch/sparc/include/uapi/asm/setup.h
>   delete mode 100644 arch/x86/include/uapi/asm/setup.h
>   rename arch/xtensa/include/{uapi => }/asm/setup.h (100%)
>   rename include/{uapi => }/asm-generic/setup.h (100%)
>
Björn noticed that I should also remove the command line size for riscv 
since it was picked up in 6.3 by Palmer...I send a v6 right now, sorry 
about that.

Alex
Alexandre Ghiti March 2, 2023, 10:09 a.m. UTC | #3
Hi Geert,

On 3/2/23 10:47, Geert Uytterhoeven wrote:
> Hi Alex,
>
> On Thu, Mar 2, 2023 at 10:35 AM Alexandre Ghiti <alexghiti@rivosinc.com> wrote:
>> This all came up in the context of increasing COMMAND_LINE_SIZE in the
>> RISC-V port.  In theory that's a UABI break, as COMMAND_LINE_SIZE is the
>> maximum length of /proc/cmdline and userspace could staticly rely on
>> that to be correct.
>>
>> Usually I wouldn't mess around with changing this sort of thing, but
>> PowerPC increased it with a5980d064fe2 ("powerpc: Bump COMMAND_LINE_SIZE
>> to 2048").  There are also a handful of examples of COMMAND_LINE_SIZE
>> increasing, but they're from before the UAPI split so I'm not quite sure
>> what that means: e5a6a1c90948 ("powerpc: derive COMMAND_LINE_SIZE from
>> asm-generic"), 684d2fd48e71 ("[S390] kernel: Append scpdata to kernel
>> boot command line"), 22242681cff5 ("MIPS: Extend COMMAND_LINE_SIZE"),
>> and 2b74b85693c7 ("sh: Derive COMMAND_LINE_SIZE from
>> asm-generic/setup.h.").
>>
>> It seems to me like COMMAND_LINE_SIZE really just shouldn't have been
>> part of the uapi to begin with, and userspace should be able to handle
>> /proc/cmdline of whatever length it turns out to be.  I don't see any
>> references to COMMAND_LINE_SIZE anywhere but Linux via a quick Google
>> search, but that's not really enough to consider it unused on my end.
>>
>> This issue was already considered in s390 and they reached the same
>> conclusion in commit 622021cd6c56 ("s390: make command line
>> configurable").
>>
>> The feedback on the v1 seemed to indicate that COMMAND_LINE_SIZE really
>> shouldn't be part of uapi, so this now touches all the ports.  I've
>> tried to split this all out and leave it bisectable, but I haven't
>> tested it all that aggressively.
>>
>> Changes since v3 <https://lore.kernel.org/all/20230214074925.228106-1-alexghiti@rivosinc.com/>:
>> * Added RB/AB
>> * Added a mention to commit 622021cd6c56 ("s390: make command line
>>    configurable") in the cover letter
> Thanks for the update!
>
>   Apparently you forgot to add your own SoB?


I do not know, should I? Palmer did all the work, I only fixed 3 minor 
things


>
> Gr{oetje,eeting}s,
>
>                          Geert
>
> --
> Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
>
> In personal conversations with technical people, I call myself a hacker. But
> when I'm talking to journalists I just say "programmer" or something like that.
>                                  -- Linus Torvalds
Geert Uytterhoeven March 2, 2023, 10:44 a.m. UTC | #4
Hi Alex,

On Thu, Mar 2, 2023 at 11:09 AM Alexandre Ghiti <alex@ghiti.fr> wrote:
> On 3/2/23 10:47, Geert Uytterhoeven wrote:
> > On Thu, Mar 2, 2023 at 10:35 AM Alexandre Ghiti <alexghiti@rivosinc.com> wrote:
> >> This all came up in the context of increasing COMMAND_LINE_SIZE in the
> >> RISC-V port.  In theory that's a UABI break, as COMMAND_LINE_SIZE is the
> >> maximum length of /proc/cmdline and userspace could staticly rely on
> >> that to be correct.
> >>
> >> Usually I wouldn't mess around with changing this sort of thing, but
> >> PowerPC increased it with a5980d064fe2 ("powerpc: Bump COMMAND_LINE_SIZE
> >> to 2048").  There are also a handful of examples of COMMAND_LINE_SIZE
> >> increasing, but they're from before the UAPI split so I'm not quite sure
> >> what that means: e5a6a1c90948 ("powerpc: derive COMMAND_LINE_SIZE from
> >> asm-generic"), 684d2fd48e71 ("[S390] kernel: Append scpdata to kernel
> >> boot command line"), 22242681cff5 ("MIPS: Extend COMMAND_LINE_SIZE"),
> >> and 2b74b85693c7 ("sh: Derive COMMAND_LINE_SIZE from
> >> asm-generic/setup.h.").
> >>
> >> It seems to me like COMMAND_LINE_SIZE really just shouldn't have been
> >> part of the uapi to begin with, and userspace should be able to handle
> >> /proc/cmdline of whatever length it turns out to be.  I don't see any
> >> references to COMMAND_LINE_SIZE anywhere but Linux via a quick Google
> >> search, but that's not really enough to consider it unused on my end.
> >>
> >> This issue was already considered in s390 and they reached the same
> >> conclusion in commit 622021cd6c56 ("s390: make command line
> >> configurable").
> >>
> >> The feedback on the v1 seemed to indicate that COMMAND_LINE_SIZE really
> >> shouldn't be part of uapi, so this now touches all the ports.  I've
> >> tried to split this all out and leave it bisectable, but I haven't
> >> tested it all that aggressively.
> >>
> >> Changes since v3 <https://lore.kernel.org/all/20230214074925.228106-1-alexghiti@rivosinc.com/>:
> >> * Added RB/AB
> >> * Added a mention to commit 622021cd6c56 ("s390: make command line
> >>    configurable") in the cover letter
> > Thanks for the update!
> >
> >   Apparently you forgot to add your own SoB?
>
> I do not know, should I? Palmer did all the work, I only fixed 3 minor
> things

If you are picking up patches, and submitting them to someone else
for upstream inclusion, you should add your own SoB.
https://elixir.bootlin.com/linux/latest/source/Documentation/process/submitting-patches.rst#L419

Gr{oetje,eeting}s,

                        Geert
Alexandre Ghiti March 2, 2023, 10:45 a.m. UTC | #5
On 3/2/23 11:44, Geert Uytterhoeven wrote:
> Hi Alex,
>
> On Thu, Mar 2, 2023 at 11:09 AM Alexandre Ghiti <alex@ghiti.fr> wrote:
>> On 3/2/23 10:47, Geert Uytterhoeven wrote:
>>> On Thu, Mar 2, 2023 at 10:35 AM Alexandre Ghiti <alexghiti@rivosinc.com> wrote:
>>>> This all came up in the context of increasing COMMAND_LINE_SIZE in the
>>>> RISC-V port.  In theory that's a UABI break, as COMMAND_LINE_SIZE is the
>>>> maximum length of /proc/cmdline and userspace could staticly rely on
>>>> that to be correct.
>>>>
>>>> Usually I wouldn't mess around with changing this sort of thing, but
>>>> PowerPC increased it with a5980d064fe2 ("powerpc: Bump COMMAND_LINE_SIZE
>>>> to 2048").  There are also a handful of examples of COMMAND_LINE_SIZE
>>>> increasing, but they're from before the UAPI split so I'm not quite sure
>>>> what that means: e5a6a1c90948 ("powerpc: derive COMMAND_LINE_SIZE from
>>>> asm-generic"), 684d2fd48e71 ("[S390] kernel: Append scpdata to kernel
>>>> boot command line"), 22242681cff5 ("MIPS: Extend COMMAND_LINE_SIZE"),
>>>> and 2b74b85693c7 ("sh: Derive COMMAND_LINE_SIZE from
>>>> asm-generic/setup.h.").
>>>>
>>>> It seems to me like COMMAND_LINE_SIZE really just shouldn't have been
>>>> part of the uapi to begin with, and userspace should be able to handle
>>>> /proc/cmdline of whatever length it turns out to be.  I don't see any
>>>> references to COMMAND_LINE_SIZE anywhere but Linux via a quick Google
>>>> search, but that's not really enough to consider it unused on my end.
>>>>
>>>> This issue was already considered in s390 and they reached the same
>>>> conclusion in commit 622021cd6c56 ("s390: make command line
>>>> configurable").
>>>>
>>>> The feedback on the v1 seemed to indicate that COMMAND_LINE_SIZE really
>>>> shouldn't be part of uapi, so this now touches all the ports.  I've
>>>> tried to split this all out and leave it bisectable, but I haven't
>>>> tested it all that aggressively.
>>>>
>>>> Changes since v3 <https://lore.kernel.org/all/20230214074925.228106-1-alexghiti@rivosinc.com/>:
>>>> * Added RB/AB
>>>> * Added a mention to commit 622021cd6c56 ("s390: make command line
>>>>     configurable") in the cover letter
>>> Thanks for the update!
>>>
>>>    Apparently you forgot to add your own SoB?
>> I do not know, should I? Palmer did all the work, I only fixed 3 minor
>> things
> If you are picking up patches, and submitting them to someone else
> for upstream inclusion, you should add your own SoB.
> https://elixir.bootlin.com/linux/latest/source/Documentation/process/submitting-patches.rst#L419


Great, thanks for the pointer, I'll do that then!


Thanks again,


Alex


> Gr{oetje,eeting}s,
>
>                          Geert
>
Alexandre Ghiti March 2, 2023, 12:38 p.m. UTC | #6
On 3/2/23 11:06, Alexandre Ghiti wrote:
> Hi Arnd,
>
> On 3/2/23 10:35, Alexandre Ghiti wrote:
>> This all came up in the context of increasing COMMAND_LINE_SIZE in the
>> RISC-V port.  In theory that's a UABI break, as COMMAND_LINE_SIZE is the
>> maximum length of /proc/cmdline and userspace could staticly rely on
>> that to be correct.
>>
>> Usually I wouldn't mess around with changing this sort of thing, but
>> PowerPC increased it with a5980d064fe2 ("powerpc: Bump COMMAND_LINE_SIZE
>> to 2048").  There are also a handful of examples of COMMAND_LINE_SIZE
>> increasing, but they're from before the UAPI split so I'm not quite sure
>> what that means: e5a6a1c90948 ("powerpc: derive COMMAND_LINE_SIZE from
>> asm-generic"), 684d2fd48e71 ("[S390] kernel: Append scpdata to kernel
>> boot command line"), 22242681cff5 ("MIPS: Extend COMMAND_LINE_SIZE"),
>> and 2b74b85693c7 ("sh: Derive COMMAND_LINE_SIZE from
>> asm-generic/setup.h.").
>>
>> It seems to me like COMMAND_LINE_SIZE really just shouldn't have been
>> part of the uapi to begin with, and userspace should be able to handle
>> /proc/cmdline of whatever length it turns out to be.  I don't see any
>> references to COMMAND_LINE_SIZE anywhere but Linux via a quick Google
>> search, but that's not really enough to consider it unused on my end.
>>
>> This issue was already considered in s390 and they reached the same
>> conclusion in commit 622021cd6c56 ("s390: make command line
>> configurable").
>>
>> The feedback on the v1 seemed to indicate that COMMAND_LINE_SIZE really
>> shouldn't be part of uapi, so this now touches all the ports. I've
>> tried to split this all out and leave it bisectable, but I haven't
>> tested it all that aggressively.
>>
>> Changes since v3 
>> <https://lore.kernel.org/all/20230214074925.228106-1-alexghiti@rivosinc.com/>:
>> * Added RB/AB
>> * Added a mention to commit 622021cd6c56 ("s390: make command line
>>    configurable") in the cover letter
>>
>> Changes since v2 
>> <https://lore.kernel.org/all/20221211061358.28035-1-palmer@rivosinc.com/>:
>> * Fix sh, csky and ia64 builds, as reported by kernel test robot
>>
>> Changes since v1 
>> <https://lore.kernel.org/all/20210423025545.313965-1-palmer@dabbelt.com/>:
>> * Touches every arch.
>>
>> base-commit-tag: next-20230207
>>
>> Palmer Dabbelt (24):
>>    alpha: Remove COMMAND_LINE_SIZE from uapi
>>    arm64: Remove COMMAND_LINE_SIZE from uapi
>>    arm: Remove COMMAND_LINE_SIZE from uapi
>>    ia64: Remove COMMAND_LINE_SIZE from uapi
>>    m68k: Remove COMMAND_LINE_SIZE from uapi
>>    microblaze: Remove COMMAND_LINE_SIZE from uapi
>>    mips: Remove COMMAND_LINE_SIZE from uapi
>>    parisc: Remove COMMAND_LINE_SIZE from uapi
>>    powerpc: Remove COMMAND_LINE_SIZE from uapi
>>    sparc: Remove COMMAND_LINE_SIZE from uapi
>>    xtensa: Remove COMMAND_LINE_SIZE from uapi
>>    asm-generic: Remove COMMAND_LINE_SIZE from uapi
>>    alpha: Remove empty <uapi/asm/setup.h>
>>    arc: Remove empty <uapi/asm/setup.h>
>>    m68k: Remove empty <uapi/asm/setup.h>
>>    arm64: Remove empty <uapi/asm/setup.h>
>>    microblaze: Remove empty <uapi/asm/setup.h>
>>    sparc: Remove empty <uapi/asm/setup.h>
>>    parisc: Remove empty <uapi/asm/setup.h>
>>    x86: Remove empty <uapi/asm/setup.h>
>>    xtensa: Remove empty <uapi/asm/setup.h>
>>    powerpc: Remove empty <uapi/asm/setup.h>
>>    mips: Remove empty <uapi/asm/setup.h>
>>    s390: Remove empty <uapi/asm/setup.h>
>>
>>   .../admin-guide/kernel-parameters.rst         |  2 +-
>>   arch/alpha/include/asm/setup.h                |  4 +--
>>   arch/alpha/include/uapi/asm/setup.h           |  7 -----
>>   arch/arc/include/asm/setup.h                  |  1 -
>>   arch/arc/include/uapi/asm/setup.h             |  6 -----
>>   arch/arm/include/asm/setup.h                  |  1 +
>>   arch/arm/include/uapi/asm/setup.h             |  2 --
>>   arch/arm64/include/asm/setup.h                |  3 ++-
>>   arch/arm64/include/uapi/asm/setup.h           | 27 -------------------
>>   arch/ia64/include/asm/setup.h                 | 10 +++++++
>>   arch/ia64/include/uapi/asm/setup.h            |  6 ++---
>>   arch/loongarch/include/asm/setup.h            |  2 +-
>>   arch/m68k/include/asm/setup.h                 |  3 +--
>>   arch/m68k/include/uapi/asm/setup.h            | 17 ------------
>>   arch/microblaze/include/asm/setup.h           |  2 +-
>>   arch/microblaze/include/uapi/asm/setup.h      | 20 --------------
>>   arch/mips/include/asm/setup.h                 |  3 ++-
>>   arch/mips/include/uapi/asm/setup.h            |  8 ------
>>   arch/parisc/include/{uapi => }/asm/setup.h    |  0
>>   arch/powerpc/include/asm/setup.h              |  2 +-
>>   arch/powerpc/include/uapi/asm/setup.h         |  7 -----
>>   arch/s390/include/asm/setup.h                 |  1 -
>>   arch/s390/include/uapi/asm/setup.h            |  1 -
>>   arch/sh/include/asm/setup.h                   |  2 +-
>>   arch/sparc/include/asm/setup.h                |  6 ++++-
>>   arch/sparc/include/uapi/asm/setup.h           | 16 -----------
>>   arch/x86/include/asm/setup.h                  |  2 --
>>   arch/x86/include/uapi/asm/setup.h             |  1 -
>>   arch/xtensa/include/{uapi => }/asm/setup.h    |  0
>>   include/asm-generic/Kbuild                    |  1 +
>>   include/{uapi => }/asm-generic/setup.h        |  0
>>   include/uapi/asm-generic/Kbuild               |  1 -
>>   32 files changed, 31 insertions(+), 133 deletions(-)
>>   delete mode 100644 arch/alpha/include/uapi/asm/setup.h
>>   delete mode 100644 arch/arc/include/uapi/asm/setup.h
>>   delete mode 100644 arch/arm64/include/uapi/asm/setup.h
>>   create mode 100644 arch/ia64/include/asm/setup.h
>>   delete mode 100644 arch/m68k/include/uapi/asm/setup.h
>>   delete mode 100644 arch/microblaze/include/uapi/asm/setup.h
>>   delete mode 100644 arch/mips/include/uapi/asm/setup.h
>>   rename arch/parisc/include/{uapi => }/asm/setup.h (100%)
>>   delete mode 100644 arch/powerpc/include/uapi/asm/setup.h
>>   delete mode 100644 arch/s390/include/uapi/asm/setup.h
>>   delete mode 100644 arch/sparc/include/uapi/asm/setup.h
>>   delete mode 100644 arch/x86/include/uapi/asm/setup.h
>>   rename arch/xtensa/include/{uapi => }/asm/setup.h (100%)
>>   rename include/{uapi => }/asm-generic/setup.h (100%)
>>
> Björn noticed that I should also remove the command line size for 
> riscv since it was picked up in 6.3 by Palmer...I send a v6 right now, 
> sorry about that.
>
> Alex
>

Hmmm when implementing the riscv patch, I noticed that the patches that 
introduce a new include/asm/setup.h file add the following SPDX header:

/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */

To me we should not add "WITH Linux-syscall-note" as this header is not 
part of the user visible headers: any opinion before I send the v5?

Thanks,

Alex