Re: [Qemu-ppc] [PATCH 4/5] configs: Add a CONFIG_UNIMP switch for the "unimplemented-device"

[Peter Maydell]

On 19 October 2018 at 17:44, Paolo Bonzini <address@hidden> wrote:
> On 19/10/2018 18:25, Philippe Mathieu-Daudé wrote:
>>
>> First because I'm using it heavily on MIPS and PPC boards, when no
>> datashits are available.
>> I'll submit that during the next merge window, although the MIPS tree
>> seems now reluctant to that kind of hobbyist work.
>>
>> Second, because it is very clean when you implement a SoC to first
>> start with an empty UNIMP region and a cpu core,
>> then declare the mmio regions for each device (still UNIMP), then you
>> can slowly add devices one at a time.
>> This let you (me, so far) push at most a dozen of tiny patches in a
>> working series, instead of a small series of a dozen of huge patches,
>> or a series of 100 tiny patches.
>
> I don't see however why it's a problem to add/remove CONFIG_UNIMP to
> default-configs though (in the Kconfig world the board would "select
> UNIMP").

Well, it's extra friction for people writing new board models,
and the benefit of having CONFIG_UNIMP is all to downstream
redistributors, not to upstream...

I'm not vetoing this patchset, but I do think that if RedHat
wants to distribute significantly-cut-down binaries then
it would be worth working on a mechanism for making that
more conveniently doable, rather than just hacking up
the very creaky default-configs/ stuff.

thanks
-- PMM