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Re: [Xen-devel] [Qemu-devel] [PATCH v7 00/42] Invert Endian bit in SPARCv9 MMU TTE
- To: Philippe Mathieu-Daudé <philmd@xxxxxxxxxx>
- From: David Gibson <david@xxxxxxxxxxxxxxxxxxxxx>
- Date: Fri, 16 Aug 2019 21:43:05 +1000
- Cc: frederic.konrad@xxxxxxxxxxx, berto@xxxxxxxxxx, qemu-block@xxxxxxxxxx, arikalo@xxxxxxxxxxxx, pasic@xxxxxxxxxxxxx, hpoussin@xxxxxxxxxxx, anthony.perard@xxxxxxxxxx, xen-devel@xxxxxxxxxxxxxxxxxxxx, balrogg@xxxxxxxxx, jasowang@xxxxxxxxxx, jiri@xxxxxxxxxxx, ehabkost@xxxxxxxxxx, b.galvani@xxxxxxxxx, eric.auger@xxxxxxxxxx, alex.williamson@xxxxxxxxxx, stefanha@xxxxxxxxxx, jsnow@xxxxxxxxxx, rth@xxxxxxxxxxx, kwolf@xxxxxxxxxx, andrew@xxxxxxxx, claudio.fontana@xxxxxxxx, crwulff@xxxxxxxxx, laurent@xxxxxxxxx, sundeep.lkml@xxxxxxxxx, michael@xxxxxxxx, qemu-ppc@xxxxxxxxxx, kbastian@xxxxxxxxxxxxxxxxxxxxx, imammedo@xxxxxxxxxx, fam@xxxxxxxxxx, peter.maydell@xxxxxxxxxx, david@xxxxxxxxxx, palmer@xxxxxxxxxx, balaton@xxxxxxxxxx, keith.busch@xxxxxxxxx, jcmvbkbc@xxxxxxxxx, hare@xxxxxxxx, sstabellini@xxxxxxxxxx, andrew.smirnov@xxxxxxxxx, deller@xxxxxx, magnus.damm@xxxxxxxxx, marcel.apfelbaum@xxxxxxxxx, atar4qemu@xxxxxxxxx, minyard@xxxxxxx, sw@xxxxxxxxxxx, yuval.shaia@xxxxxxxxxx, qemu-s390x@xxxxxxxxxx, qemu-arm@xxxxxxxxxx, peter.chubb@xxxxxxxxxxxx, clg@xxxxxxxx, shorne@xxxxxxxxx, qemu-riscv@xxxxxxxxxx, i.mitsyanko@xxxxxxxxx, cohuck@xxxxxxxxxx, amarkovic@xxxxxxxxxxxx, jan.kiszka@xxxxxx, aurelien@xxxxxxxxxxx, pburton@xxxxxxxxxxxx, sagark@xxxxxxxxxxxxxxxxx, green@xxxxxxxxxxxxxx, kraxel@xxxxxxxxxx, edgar.iglesias@xxxxxxxxx, gxt@xxxxxxxxxxxxxxx, robh@xxxxxxxxxx, borntraeger@xxxxxxxxxx, joel@xxxxxxxxx, antonynpavlov@xxxxxxxxx, chouteau@xxxxxxxxxxx, lersek@xxxxxxxxxx, Andrew.Baumann@xxxxxxxxxxxxx, mreitz@xxxxxxxxxx, walling@xxxxxxxxxxxxx, dmitry.fleytman@xxxxxxxxx, mst@xxxxxxxxxx, mark.cave-ayland@xxxxxxxxxxxx, qemu-devel@xxxxxxxxxx, jslaby@xxxxxxx, marex@xxxxxxx, proljc@xxxxxxxxx, marcandre.lureau@xxxxxxxxxx, alistair@xxxxxxxxxxxxx, paul.durrant@xxxxxxxxxx, tony.nguyen@xxxxxx, xiaoguangrong.eric@xxxxxxxxx, huth@xxxxxxxxxxxxx, jcd@xxxxxxxxxxxxxxx, pbonzini@xxxxxxxxxx, stefanb@xxxxxxxxxxxxx
- Delivery-date: Fri, 16 Aug 2019 12:04:58 +0000
- List-id: Xen developer discussion <xen-devel.lists.xenproject.org>
On Fri, Aug 16, 2019 at 11:58:05AM +0200, Philippe Mathieu-Daudé wrote:
> Hi Tony,
>
> On 8/16/19 8:28 AM, tony.nguyen@xxxxxx 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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