On Fri, 2017-11-10 at 14:42 -0800, Deepa Dinamani wrote:
> From: Arnd Bergmann <[email protected]>
>
> There are a total of 53 system calls (aside from ioctl) that pass a time_t
> or derived data structure as an argument, and in order to extend time_t
> to 64-bit, we have to replace them with new system calls and keep providing
> backwards compatibility.
>
> To avoid adding completely new and untested code for this purpose, we
> introduce a new CONFIG_64BIT_TIME symbol. Every architecture that supports
> new 64 bit time_t syscalls enables this config via ARCH_HAS_64BIT_TIME.
>
> After this is done for all architectures, the CONFIG_64BIT_TIME symbol
> can be made a user-selected option, to enable users to build a kernel
> that only provides y2038-safe system calls by making 32 time_t syscalls
> conditionally included based on the above config.
I don't understand why we would want to change the semantics of
CONFIG_64BIT_TIME symbol from "enable 64-bit time support" to "disable
32-bit time support".
Why not add two config symbols:
config 32BIT_TIME
def_bool COMPAT || !64BIT
config 64BIT_TIME
def_bool ARCH_HAS_64BIT_TIME
and then make 32BIT_TIME user-configurable later?
> Signed-off-by: Arnd Bergmann <[email protected]>
> Signed-off-by: Deepa Dinamani <[email protected]>
> ---
> arch/Kconfig | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 8911ff37335a..3266ac1a4ff7 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -875,6 +875,17 @@ config OLD_SIGACTION
> config COMPAT_OLD_SIGACTION
> bool
>
> +config ARCH_HAS_64BIT_TIME
> + def_bool n
> +
> +config CONFIG_64BIT_TIME
The CONFIG_ prefix is added by kconfig scripts and shouldn't be used in
the Kconfig file.
Ben.
> + def_bool ARCH_HAS_64BIT_TIME
> + help
> + This should be selected by all architectures that need to support
> + new system calls with a 64-bit time_t. This is relevant on all 32-bit
> + architectures, and 64-bit architectures as part of compat syscall
> + handling.
> +
> config ARCH_NO_COHERENT_DMA_MMAP
> bool
>
--
Ben Hutchings
Software Developer, Codethink Ltd.
On Fri, Dec 8, 2017 at 8:53 AM, Ben Hutchings
<[email protected]> wrote:
> On Fri, 2017-11-10 at 14:42 -0800, Deepa Dinamani wrote:
>> From: Arnd Bergmann <[email protected]>
>>
>> There are a total of 53 system calls (aside from ioctl) that pass a time_t
>> or derived data structure as an argument, and in order to extend time_t
>> to 64-bit, we have to replace them with new system calls and keep providing
>> backwards compatibility.
>>
>> To avoid adding completely new and untested code for this purpose, we
>> introduce a new CONFIG_64BIT_TIME symbol. Every architecture that supports
>> new 64 bit time_t syscalls enables this config via ARCH_HAS_64BIT_TIME.
>>
>> After this is done for all architectures, the CONFIG_64BIT_TIME symbol
>> can be made a user-selected option, to enable users to build a kernel
>> that only provides y2038-safe system calls by making 32 time_t syscalls
>> conditionally included based on the above config.
>
> I don't understand why we would want to change the semantics of
> CONFIG_64BIT_TIME symbol from "enable 64-bit time support" to "disable
> 32-bit time support".
>
> Why not add two config symbols:
>
> config 32BIT_TIME
> def_bool COMPAT || !64BIT
>
> config 64BIT_TIME
> def_bool ARCH_HAS_64BIT_TIME
>
> and then make 32BIT_TIME user-configurable later?
This was already discussed on the review and we have an updated version:
https://lkml.org/lkml/2017/11/27/938
>> Signed-off-by: Arnd Bergmann <[email protected]>
>> Signed-off-by: Deepa Dinamani <[email protected]>
>> ---
>> arch/Kconfig | 11 +++++++++++
>> 1 file changed, 11 insertions(+)
>>
>> diff --git a/arch/Kconfig b/arch/Kconfig
>> index 8911ff37335a..3266ac1a4ff7 100644
>> --- a/arch/Kconfig
>> +++ b/arch/Kconfig
>> @@ -875,6 +875,17 @@ config OLD_SIGACTION
>> config COMPAT_OLD_SIGACTION
>> bool
>>
>> +config ARCH_HAS_64BIT_TIME
>> + def_bool n
>> +
>> +config CONFIG_64BIT_TIME
>
> The CONFIG_ prefix is added by kconfig scripts and shouldn't be used in
> the Kconfig file.
Yes, this was a typo and was fixed by the next revision which has
already been posted:
https://lkml.org/lkml/2017/11/27/938
-Deepa
On Fri, 2017-12-08 at 09:01 -0800, Deepa Dinamani wrote:
> On Fri, Dec 8, 2017 at 8:53 AM, Ben Hutchings
> > <[email protected]> wrote:
> > On Fri, 2017-11-10 at 14:42 -0800, Deepa Dinamani wrote:
> > > From: Arnd Bergmann <[email protected]>
> > >
> > > There are a total of 53 system calls (aside from ioctl) that pass a time_t
> > > or derived data structure as an argument, and in order to extend time_t
> > > to 64-bit, we have to replace them with new system calls and keep providing
> > > backwards compatibility.
> > >
> > > To avoid adding completely new and untested code for this purpose, we
> > > introduce a new CONFIG_64BIT_TIME symbol. Every architecture that supports
> > > new 64 bit time_t syscalls enables this config via ARCH_HAS_64BIT_TIME.
> > >
> > > After this is done for all architectures, the CONFIG_64BIT_TIME symbol
> > > can be made a user-selected option, to enable users to build a kernel
> > > that only provides y2038-safe system calls by making 32 time_t syscalls
> > > conditionally included based on the above config.
> >
> > I don't understand why we would want to change the semantics of
> > CONFIG_64BIT_TIME symbol from "enable 64-bit time support" to "disable
> > 32-bit time support".
> >
> > Why not add two config symbols:
> >
> > config 32BIT_TIME
> > def_bool COMPAT || !64BIT
> >
> > config 64BIT_TIME
> > def_bool ARCH_HAS_64BIT_TIME
> >
> > and then make 32BIT_TIME user-configurable later?
>
> This was already discussed on the review and we have an updated version:
>
> https://lkml.org/lkml/2017/11/27/938
Sorry, I'll move on to reviewing that.
Ben.
--
Ben Hutchings
Software Developer, Codethink Ltd.