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hwrng: nomadik: add ARM_AMBA dependency

PATCH In review Arnd Bergmann 4 participants 4 messages Jul 29, 2025 – Oct 6, 2025

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Arnd Bergmann

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#0 lore raw

PATCH 1/1 hwrng: nomadik: add ARM_AMBA dependency

From: Arnd Bergmann <[email protected]>

Compile-testing this driver is only possible when the AMBA bus driver is available in the kernel:

x86_64-linux-ld: drivers/char/hw_random/nomadik-rng.o: in function `nmk_rng_remove':
nomadik-rng.c:(.text+0x67): undefined reference to `amba_release_regions'
x86_64-linux-ld: drivers/char/hw_random/nomadik-rng.o: in function `nmk_rng_probe':
nomadik-rng.c:(.text+0xee): undefined reference to `amba_request_regions'
x86_64-linux-ld: nomadik-rng.c:(.text+0x18d): undefined reference to `amba_release_regions'

The was previously implied by the 'depends on ARCH_NOMADIK', but needs to be specified for the COMPILE_TEST case.

Fixes d5e93b3374e4 ("hwrng: Kconfig - Add helper dependency on COMPILE_TEST")
Signed-off-by Arnd Bergmann <[email protected]>
---
 drivers/char/hw_random/Kconfig | 1 +
 1 file changed, 1 insertion(+)
drivers/char/hw_random/Kconfig +1 -0
index 3227dcaa9111..aef4406973f3 100644
@@ -312,6 +312,7 @@ config HW_RANDOM_INGENIC_TRNG
 config HW_RANDOM_NOMADIK
 	tristate "ST-Ericsson Nomadik Random Number Generator support"
 	depends on ARCH_NOMADIK || COMPILE_TEST
+	depends on ARM_AMBA
 	default HW_RANDOM
 	help
 	  This driver provides kernel-side support for the Random Number
Signature · 1 line
2.39.5
maintainer
#1 lore raw
Quoted 11 lines · Arnd Bergmann

From: Arnd Bergmann <[email protected]>

Compile-testing this driver is only possible when the AMBA bus driver is available in the kernel:

x86_64-linux-ld: drivers/char/hw_random/nomadik-rng.o: in function `nmk_rng_remove':
nomadik-rng.c:(.text+0x67): undefined reference to `amba_release_regions'
x86_64-linux-ld: drivers/char/hw_random/nomadik-rng.o: in function `nmk_rng_probe':
nomadik-rng.c:(.text+0xee): undefined reference to `amba_request_regions'
x86_64-linux-ld: nomadik-rng.c:(.text+0x18d): undefined reference to `amba_release_regions'

Quoted 8 lines

The was previously implied by the 'depends on ARCH_NOMADIK', but needs to be specified for the COMPILE_TEST case.

Fixes d5e93b3374e4 ("hwrng: Kconfig - Add helper dependency on COMPILE_TEST")
Signed-off-by Arnd Bergmann <[email protected]>
---
 drivers/char/hw_random/Kconfig | 1 +
 1 file changed, 1 insertion(+)

Patch applied. Thanks.

Signature · 3 lines
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
#2 lore raw
In reply to Arnd Bergmann

Hi Arnd,

Quoted 11 lines · Arnd Bergmann

From: Arnd Bergmann <[email protected]>

Compile-testing this driver is only possible when the AMBA bus driver is available in the kernel:

x86_64-linux-ld: drivers/char/hw_random/nomadik-rng.o: in function `nmk_rng_remove':
nomadik-rng.c:(.text+0x67): undefined reference to `amba_release_regions'
x86_64-linux-ld: drivers/char/hw_random/nomadik-rng.o: in function `nmk_rng_probe':
nomadik-rng.c:(.text+0xee): undefined reference to `amba_request_regions'
x86_64-linux-ld: nomadik-rng.c:(.text+0x18d): undefined reference to `amba_release_regions'

Quoted 5 lines

The was previously implied by the 'depends on ARCH_NOMADIK', but needs to be specified for the COMPILE_TEST case.

Fixes d5e93b3374e4 ("hwrng: Kconfig - Add helper dependency on COMPILE_TEST")
Signed-off-by Arnd Bergmann <[email protected]>

Thanks for your patch, which is now commit efaa2d815a0e4d1c ("hwrng:
nomadik - add ARM_AMBA dependency") upstream.

drivers/char/hw_random/Kconfig config HW_RANDOM_INGENIC_TRNG · line 318

Quoted 10 lines
drivers/char/hw_random/Kconfig +1 -0
@@ -312,6 +312,7 @@ config HW_RANDOM_INGENIC_TRNG
 config HW_RANDOM_NOMADIK
        tristate "ST-Ericsson Nomadik Random Number Generator support"
        depends on ARCH_NOMADIK || COMPILE_TEST
+       depends on ARM_AMBA
        default HW_RANDOM
        help
          This driver provides kernel-side support for the Random Number

After seeing CONFIG_HW_RANDOM_NOMADIK disappear from m68k all{mod,yes}config, I became intrigued, as it did build fine before? If CONFIG_ARM_AMBA is not enabled, both __amba_driver_register() and amba_driver_unregister() become static inline dummies, and the rest of the code and data is not referenced, thus optimized away by the compiler. I verified this is the case on amd64 allmodconfig, too. How come this failed for you?

Gr{oetje,eeting}s,

Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- [email protected]

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

#3 lore raw
Quoted 32 lines · Geert Uytterhoeven
Quoted 11 lines · Arnd Bergmann

From: Arnd Bergmann <[email protected]>

Compile-testing this driver is only possible when the AMBA bus driver is available in the kernel:

x86_64-linux-ld: drivers/char/hw_random/nomadik-rng.o: in function `nmk_rng_remove':
nomadik-rng.c:(.text+0x67): undefined reference to `amba_release_regions'
x86_64-linux-ld: drivers/char/hw_random/nomadik-rng.o: in function `nmk_rng_probe':
nomadik-rng.c:(.text+0xee): undefined reference to `amba_request_regions'
x86_64-linux-ld: nomadik-rng.c:(.text+0x18d): undefined reference to `amba_release_regions'

Quoted 5 lines

The was previously implied by the 'depends on ARCH_NOMADIK', but needs to be specified for the COMPILE_TEST case.

Fixes d5e93b3374e4 ("hwrng: Kconfig - Add helper dependency on COMPILE_TEST")
Signed-off-by Arnd Bergmann <[email protected]>

Thanks for your patch, which is now commit efaa2d815a0e4d1c ("hwrng:
nomadik - add ARM_AMBA dependency") upstream.

drivers/char/hw_random/Kconfig config HW_RANDOM_INGENIC_TRNG · line 318

Quoted 10 lines
drivers/char/hw_random/Kconfig +1 -0
@@ -312,6 +312,7 @@ config HW_RANDOM_INGENIC_TRNG
 config HW_RANDOM_NOMADIK
        tristate "ST-Ericsson Nomadik Random Number Generator support"
        depends on ARCH_NOMADIK || COMPILE_TEST
+       depends on ARM_AMBA
        default HW_RANDOM
        help
          This driver provides kernel-side support for the Random Number
Quoted 7 lines

After seeing CONFIG_HW_RANDOM_NOMADIK disappear from m68k all{mod,yes}config, I became intrigued, as it did build fine before? If CONFIG_ARM_AMBA is not enabled, both __amba_driver_register() and amba_driver_unregister() become static inline dummies, and the rest of the code and data is not referenced, thus optimized away by the compiler. I verified this is the case on amd64 allmodconfig, too. How come this failed for you?

I believe this was the result of new build options getting adding to the randconfig test matrix. If for any reason the __amba_driver_register() function does not get inlined, the caller will still have a permanent reference to the amba_driver structure, and the rest of the file does not get removed by dead-code elimination.

Most likely this change happens because the __init attribute on the module_init function puts it into a separate section from the __amba_driver_register() function, causing the compiler to refuse inlining them. Marking __amba_driver_register() as __always_inline, or changing the amba_driver_register() macro to not pass the pointer should also work here.

Arnd