[lowrisc-dev] Support for Fedora / compressed extension

Tommy Thorn tommy at thorn.ws
Sun Apr 1 23:57:06 BST 2018

FWIW, I agree.  It was decided prematurely at a time where all implementations were fairly simple and for which C does not carry as much burden.

It is the greatest irony that RISC-V went to great length to avoid the pitfalls that burden superscalar implementation - and then went on to imposed variable length instructions, split over cache lines.



> On Apr 1, 2018, at 13:57, Luke Kenneth Casson Leighton <lkcl at lkcl.net> wrote:
>> On Sun, Apr 1, 2018 at 9:48 PM, Alex Bradbury <asb at lowrisc.org> wrote:
>>> On 1 April 2018 at 21:31, Richard W.M. Jones <rjones at redhat.com> wrote:
>>> Hi, I was going to try v0.5 on my Nexys 4 DDR.  However I believe
>>> that this version doesn't support the Compressed extension.  I
>>> disassembled the sample bbl and there are no short instructions.
>>> Is support for the C extension available and/or planned?
>> Hi Richard,
>> Thanks for taking a look. You're correct that we're currently based on
>> an old version of Rocket which doesn't support the compressed
>> extension - upstream refactorings have made it difficult to keep up to
>> date. We do intend to support the C extension, though I can't give a
>> ETA right now. Sadly this means we can't (for now) directly consume
>> the awesome work you and your colleagues have been doing on Fedora
>> RISC-V - but look forward to doing so in the not too distant future.
> alex, dr kimmet: i... did try (partly on your behalf) to get across
> to the RISC-V Foundation how... deeply unimpressed i was that RV64GC
> had been chosen as the default unix standard without *any* kind of
> wider consultation, not even with the RISC-V members.
> unfortunately my usual direct, bluntly honest and completely
> undiplomatic communications style, which i mirror in real life by
> wearing 12 GBP steel toe-capped boots, bought from Douglas Dairy
> Supplies in Stranraer, did not go down well.
> sorry.
> l.

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