[lowrisc-dev] Support for Fedora / compressed extension
Dr Jonathan Kimmitt
jrrk2 at cam.ac.uk
Mon Apr 2 13:02:25 BST 2018
If Fedora can run in spike with memory limited to 128M, then there is no
reason why an upgraded Rocket with the C
extension cannot run it on an Nexys4DDR. But we cannot give a timescale
to fix this because there are other unidentified
issues to be fixed as well. And it is a little difficult to rebase
because major refactoring has gone on since then.
The biggest of these has been the introduction of TileLink-2, and it is
not really practical to backport any of those features to the TileLink-1
design that we have.
So our next release date and contents is uncertain, but as much IP and
functionality as we can will be reused.
On 02/04/18 12:27, Manuel A. Fernandez Montecelo wrote:
> 2018-04-02 09:23 Dr Jonathan Kimmitt:
>> Dear Richard,
>> My mistake, lowRISC-v0.5 runs a lightweight source based distribution
>> based on RISCV-poky, using our modified 1.9.1 kernel and device
>> drivers which have not been upstreamed. It would be perfectly
>> possible to compile Fedora without compression but this would just
>> move the bottleneck to a different place which is that the emulator
>> is over a hundred times slower than a modern PC, and limited to 128M
>> of RAM. Even running yum takes more than this at times. Swapping is
>> also slow because it relies on individual writes to SD-card with 4
>> bits @ 5MHz, which itself has internal latency. In addition network
>> access is throttled to about 2 megabytes per second due to TCP stack
>> and bus width considerations.
>> With the best will in the world most mainstream distributions have
>> more or less abandoned the embedded market by preferring heavyweight
>> python based system tools which trade off memory for performance
>> (feel free to dispute this sweeping generalisation, I know apt can
>> run on the iPhone). I am aware of course that Python has many
>> benefits in robustness and foolproofing.
> apt is C++, though, and the main source of "memory usage" at runtime
> comes from the thousands of packages available in a full-fledged
> GNU/Linux distribution.
> Not sure in an FPGA, but it runs fine even in spike, AFAICR.
> Aside from this... dispute :) I suppose that Richard's question is more
> like: will you support the C extension at some point, so lowRISC will be
> able to run Fedora/Debian/etc. in the near future?
> One doesn't always need to run apt/dnf/yum etc. to be able to use
> thousands of packages precompiled. One can just copy the file and
> install with dpkg or rpm for example, which are much less demanding.
More information about the lowrisc-dev