Re: [Qemu-devel] [PATCH v7 00/42] Invert Endian bit in SPARCv9 MMU TTE

[David Gibson]

On Fri, Aug 16, 2019 at 11:58:05AM +0200, Philippe Mathieu-Daudé wrote:
> Hi Tony,
> 
> On 8/16/19 8:28 AM, address@hidden wrote:
> > This patchset implements the IE (Invert Endian) bit in SPARCv9 MMU TTE.
> > 
> > v7:
> [...]
> > - Re-declared many native endian devices as little or big endian. This is 
> > why
> >   v7 has +16 patches.
> 
> Why are you doing that? What is the rational?
> 
> Anyhow if this not required by your series, you should split it out of
> it, and send it on your principal changes are merged.
> I'm worried because this these new patches involve many subsystems (thus
> maintainers) and reviewing them will now take a fair amount of time.
> 
> > For each device declared with DEVICE_NATIVE_ENDIAN, find the set of
> > targets from the set of target/hw/*/device.o.
> >
> > If the set of targets are all little or all big endian, re-declare
> > the device endianness as DEVICE_LITTLE_ENDIAN or DEVICE_BIG_ENDIAN
> > respectively.
> 
> If only little endian targets use a device, that doesn't mean the device
> is designed in little endian...
> 
> Then if a big endian target plan to use this device, it will require
> more work and you might have introduced regressions...

Uh.. only if they make the version of the device on a big endian
target big endian.  Which is a terrible idea - if you know a hardware
designer planning to do this, please slap them.

-- 
David Gibson                    | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au  | minimalist, thank you.  NOT _the_ _other_
                                | _way_ _around_!
http://www.ozlabs.org/~dgibson

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