Gregory Maxwell gmaxw...@gmail.com writes:
It's portable to anything that can run the relevant VMs. Uh
provided you don't mind cross compiling everything from an unbuntu VM.
It certainly would be nice if the trusted-computing-base for gitian
were a bit smaller, thats an area for long term improvement for sure.
Thanks - I'll look forward to this being portable someday. Right now it
sounds similar to a windows binary but you can use wine with
substitution of variables :-) People may want to look at the NetBSD
build system, which I think achieves bit-identical builds from different
hosts (but I haven't really checked), by having the toolchain be part of
the source and building cross-compilers from host to target and then
using those to build the system.
Say Bitcoin used a backing database which had an unknown a bug where
any item with a key that begins with 0xDEADBEEF returns not found when
queried, even if its in the DB. Once discovered, any database library
would want to fix that quickly and they'd fix it in a point release
without reservation. They might not even release note that particular
fix it if went along with some others, it could even be fixed
accidentally.
Now say that we have a state where half the Bitcoin network is running
the old buggy version, and half is running the fixed version. Someone
creates a transaction with ID 0xDEADBEEF... and then subsequently
spends the output of that transaction. This could be by pure chance or
it could be a malicious act.
To half the network that spending transaction looks like someone
spending coin from nowhere, a violation of the rules. The consensus
would then fork, effectively partitioning the network. On each fork
any coin could be spent twice, and the fork will only be resolvable by
one side or the other abandoning their state (generally the more
permissive side would need to be abandoned because the permissive one
is tolerant of the restrictive one's behavior) by manually downgrading
or patching software. As a result of this parties who believed some
of their transactions were safely settled would find them reversed by
people who exploited the inconsistent consensus.
Thanks for the explanation - that indeed makes sense.
multiple packages is difficult, and runs into A wants only n of C, while
B wants only m.
My understanding is that gentoo is actually able to handle this (and
does, for Bitcoin)— and really I presume just about everything else
could with enough effort. I certainly wouldn't ask anyone else to do
that. If you're really getting into the rathole of building separate
libraries just for Bitcoin the value of packaging it goes away.
Well, if you insist on not having updates and bugfixes, then either it's
the included version or there's a special package just for you.
Typically packaging systems don't like included versions because often a
package will have a security bug fixed long before there are updates of
packages that bundle that fixed version.But given bitcoin's special
needs, that means you have to stay on top of these dependent included
packages and re-release if there are security fixes (that don't break
consensus).
Running a complete set of tests is a start— though the unit tests are
not and cannot be adequate. There is a full systems testing harnesses
which should be used on new platforms. Even that though isn't really
adequate, as it is currently infeasible to even achieve complete test
coverage in things like cryptographic libraries and database
environments.
It would be nice if the regression tests were installed and it were
normal culturallly for end-users to run them.
Thanks again for the explanation; I understand where you are coming from
now.
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