design.html: backpedal a bit on POWER9

Supporting POWER9 isn't going to be as easy as I'd initially hoped.
This patch aims to explain that there are blockers that I'd need help
overcoming to be able to support it, even though I'd still like to.

I don't want to be promising anything I can't deliver on, and I now
know that it's very unlikely I'll be able to deliver on this without
help.

Reported-by: Molly Miller <mm@m-squa.red>
Message-Id: <20201118120116.21390-1-hi@alyssa.is>

1 files changed, 20 insertions, 12 deletions

diff --git a/design.html b/design.html
index 0474bf9..5b1168c 100644
--- a/design.html
+++ b/design.html
@@ -128,18 +128,26 @@ Management Engine</a>
 / <a href="https://en.wikipedia.org/wiki/AMD_Platform_Security_Processor">AMD
 Platform Security Processor</a>.
 
-<p>So, Spectrum will additionally have
-first class support for at least ppc64le.  This architecture has been
-chosen because it is the only other architecture that can come close
-to the sheer performance x86_64 can offer at the high end, and
-because, in stark contrast to x86_64, it is possible to buy a new
-ppc64le (POWER9) system that does not require any proprietary firmware
-that cannot be inspected and audited.  It is a goal of the project to
-build all packages, x86_64 and ppc64le, on POWER9 hardware.  Even if a
-user has to trust the x86_64 computer available to them, anti-freedom
-firmware, undocumented backdoors and all, it would be a disservice to
-them to force them to use packages built on other such untrustworthy
-hardware.
+<p>
+I would like Spectrum to additionally have first class support for at
+least ppc64le.  This is the only other architecture that can come
+close to the sheer performance x86_64 can offer at the high end, and
+in stark contrast to x86_64, it is possible to buy a new ppc64le
+(POWER9) system that does not require any proprietary firmware that
+cannot be inspected and audited.  A blocker for POWER9 support is an
+support in crosvm for virtualizing that architecture, which is outside
+the expertise of anybody currently working on Spectrum but would be a
+very welcome contribution.
+
+<p>
+Ideally, all Spectrum packages, x86_64 and ppc64le, would be built on
+POWER9 hardware.  Even if a user has to trust the x86_64 computer
+available to them, anti-freedom firmware, undocumented backdoors and
+all, they would be able to benefit from binary packages that were
+built on trustworthy hardware without these limitations.
+Unfortunately, preliminary research has shown that x86_64
+virtualization on POWER9 is not currently sufficiantly performant for
+this to be feasible.
 
 <p>
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