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SubjectRe: [PATCH 1/4] isa: Allow ISA-style drivers on modern systems
On Mon, May 23, 2016 at 10:58:41AM -0400, William Breathitt Gray wrote:
> Several modern devices, such as PC/104 cards, are expected to run on
> modern systems via an ISA bus interface. Since ISA is a legacy interface
> for most modern architectures, ISA support should remain disabled in
> general. Support for ISA-style drivers should be enabled on a per driver
> basis.
>
> To allow ISA-style drivers on modern systems, this patch introduces the
> ISA_BUS_API and ISA_BUS Kconfig options. The X86 ISA bus driver will now
> build conditionally on the ISA_BUS_API Kconfig option, which defaults to
> the legacy ISA Kconfig option. The ISA_BUS Kconfig option allows the
> ISA_BUS_API Kconfig option to be selected on architectures which do not
> enable ISA (e.g. X86_64).
>
> For now, the ISA_BUS Kconfig option is only be available on X86
> architectures. Support for other architectures may be added as required.
>
> Cc: Linus Torvalds <torvalds@linux-foundation.org>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
> ---
> arch/x86/Kconfig | 13 +++++++++++++
> drivers/base/Makefile | 2 +-
> 2 files changed, 14 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 0a7b885..a41c0b8 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -2439,6 +2439,19 @@ config PCI_CNB20LE_QUIRK
>
> source "drivers/pci/Kconfig"
>
> +config ISA_BUS_API
> + def_bool ISA
> +
> +config ISA_BUS
> + bool "ISA-style bus support on modern systems" if (X86 && EXPERT)
> + default y

Sure you want it enabled by default ?

> + select ISA_BUS_API
> + help
> + Enables ISA-style drivers on modern systems. This is necessary to
> + support PC/104 devices on X86_64 platforms.
> +
> + If unsure, say Y.
> +
> # x86_64 have no ISA slots, but can have ISA-style DMA.
> config ISA_DMA_API
> bool "ISA-style DMA support" if (X86_64 && EXPERT)
> diff --git a/drivers/base/Makefile b/drivers/base/Makefile
> index 6b2a84e..2609ba2 100644
> --- a/drivers/base/Makefile
> +++ b/drivers/base/Makefile
> @@ -10,7 +10,7 @@ obj-$(CONFIG_DMA_CMA) += dma-contiguous.o
> obj-y += power/
> obj-$(CONFIG_HAS_DMA) += dma-mapping.o
> obj-$(CONFIG_HAVE_GENERIC_DMA_COHERENT) += dma-coherent.o
> -obj-$(CONFIG_ISA) += isa.o
> +obj-$(CONFIG_ISA_BUS_API) += isa.o

Unless I am missing something, this is insufficient, and I am a bit surprised
that it actually works. include/linux/isa.h declares isa_register_driver()
and isa_unregister_driver() as dummies if CONFIG_ISA is not enabled.
Doesn't this cause a compile error ? Confused.

Thanks,
Guenter

> obj-$(CONFIG_FW_LOADER) += firmware_class.o
> obj-$(CONFIG_NUMA) += node.o
> obj-$(CONFIG_MEMORY_HOTPLUG_SPARSE) += memory.o
> --
> 2.7.3
>
> --
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