[PATCH 2/9] kernel: change CONFIG_HW_RANDOM default to y

[Elliott Mitchell]

On Fri, Apr 28, 2023 at 10:29:29AM -0600, Philip Prindeville wrote:
> Why isn't this migrating upwards into target/linux/generic/config-5.15 and target/linux/generic/config-5.10 in that case?
> 
> And for the platforms where it was turned off, like target/linux/armvirt/32/config-5.15, why isn't that staying unchanged?

I'm guessing you're unaware of a subtlety of how the .config system
actually works.  Take a second look, some handy examples:

> > On Apr 22, 2023, at 11:46 AM, Elliott Mitchell <ehem+openwrt at m5p.com> wrote:

> > diff --git a/target/linux/armvirt/32/config-5.10 b/target/linux/armvirt/32/config-5.10
> > index 3c6443bcbf..2f7cd03b5f 100644
> > --- a/target/linux/armvirt/32/config-5.10
> > +++ b/target/linux/armvirt/32/config-5.10
> > @@ -47,6 +47,7 @@ CONFIG_EDAC_ATOMIC_SCRUB=y
> > CONFIG_GENERIC_VDSO_32=y
> > CONFIG_HARDEN_BRANCH_PREDICTOR=y
> > CONFIG_HAVE_SMP=y
> > +CONFIG_HW_RANDOM=n
> > CONFIG_HZ_FIXED=0
> > CONFIG_HZ_PERIODIC=y
> > CONFIG_MIGHT_HAVE_CACHE_L2X0=y
> > diff --git a/target/linux/armvirt/32/config-5.15 b/target/linux/armvirt/32/config-5.15
> > index bf6e2a5cde..bb2a7a320f 100644
> > --- a/target/linux/armvirt/32/config-5.15
> > +++ b/target/linux/armvirt/32/config-5.15
> > @@ -49,6 +49,7 @@ CONFIG_GENERIC_IRQ_MULTI_HANDLER=y
> > CONFIG_GENERIC_VDSO_32=y
> > CONFIG_HARDEN_BRANCH_PREDICTOR=y
> > CONFIG_HAVE_SMP=y
> > +CONFIG_HW_RANDOM=n
> > CONFIG_HZ_FIXED=0
> > CONFIG_HZ_PERIODIC=y
> > CONFIG_MIGHT_HAVE_CACHE_L2X0=y


> > diff --git a/target/linux/armvirt/64/config-5.10 b/target/linux/armvirt/64/config-5.10
> > index 275fe4571d..af46939ad2 100644
> > --- a/target/linux/armvirt/64/config-5.10
> > +++ b/target/linux/armvirt/64/config-5.10
> > @@ -102,7 +102,6 @@ CONFIG_GPIO_GENERIC=y
> > CONFIG_GPIO_GENERIC_PLATFORM=y
> > CONFIG_HDMI=y
> > CONFIG_HOLES_IN_ZONE=y
> > -CONFIG_HW_RANDOM=y
> > CONFIG_HW_RANDOM_VIRTIO=y
> > CONFIG_I2C=y
> > CONFIG_I2C_ALGOBIT=y
> > diff --git a/target/linux/armvirt/64/config-5.15 b/target/linux/armvirt/64/config-5.15
> > index 19ae3dc0cf..88f2f64cde 100644
> > --- a/target/linux/armvirt/64/config-5.15
> > +++ b/target/linux/armvirt/64/config-5.15
> > @@ -103,7 +103,6 @@ CONFIG_GENERIC_FIND_FIRST_BIT=y
> > CONFIG_GPIO_GENERIC=y
> > CONFIG_GPIO_GENERIC_PLATFORM=y
> > CONFIG_HDMI=y
> > -CONFIG_HW_RANDOM=y
> > CONFIG_HW_RANDOM_ARM_SMCCC_TRNG=y
> > CONFIG_HW_RANDOM_VIRTIO=y
> > CONFIG_I2C=y
> > diff --git a/target/linux/ath25/config-5.10 b/target/linux/ath25/config-5.10
> > index ef764820e4..41e65c72ad 100644


> > diff --git a/target/linux/generic/config-5.10 b/target/linux/generic/config-5.10
> > index f6f1fb0278..853c13852d 100644
> > --- a/target/linux/generic/config-5.10
> > +++ b/target/linux/generic/config-5.10
> > @@ -2343,7 +2343,7 @@ CONFIG_HPET_MMAP_DEFAULT=y
> > # CONFIG_HWSPINLOCK is not set
> > # CONFIG_HWSPINLOCK_OMAP is not set
> > CONFIG_HW_PERF_EVENTS=y
> > -# CONFIG_HW_RANDOM is not set
> > +CONFIG_HW_RANDOM=y
> > # CONFIG_HW_RANDOM_AMD is not set
> > # CONFIG_HW_RANDOM_ATMEL is not set
> > # CONFIG_HW_RANDOM_BA431 is not set
> > diff --git a/target/linux/generic/config-5.15 b/target/linux/generic/config-5.15
> > index ac75a480a1..bf38732b31 100644
> > --- a/target/linux/generic/config-5.15
> > +++ b/target/linux/generic/config-5.15
> > @@ -2444,7 +2444,7 @@ CONFIG_HPET_MMAP_DEFAULT=y
> > # CONFIG_HWSPINLOCK is not set
> > # CONFIG_HWSPINLOCK_OMAP is not set
> > CONFIG_HW_PERF_EVENTS=y
> > -# CONFIG_HW_RANDOM is not set
> > +CONFIG_HW_RANDOM=y
> > # CONFIG_HW_RANDOM_AMD is not set
> > # CONFIG_HW_RANDOM_ARM_SMCCC_TRNG is not set
> > # CONFIG_HW_RANDOM_ATMEL is not set

armvirt/32 previously had it off and it is still off.  armvirt/64
previously had it on and it is still on.

Most similar systems would treat "# <option> is not set" as undefined or
no preference (use the default value).  The Linux kernel system treats
this as "no" due to the history of the system.  Yet it also honors "n"
as "no".

I tend to prefer "n" as it hints at a value being deliberately chosen,
instead of being left unset/undefined.


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