It seems we are doing pre-training every 6 months, and post-training every 4-8 weeks now.
209 karma · joined March 27, 2017
It seems we are doing pre-training every 6 months, and post-training every 4-8 weeks now.
[0] https://www.lrt.lt/en/news-in-english/19/2461209/will-lithua...
Again, I was surprised by the number of firmware and driver issues since RNDA1/2/3 have been around for years now.
MilkV Oasis with SG2380 would be the end-game for majority of developers, but they are definitely loosing money if they keep starting price at 120 USD. They don't have it frozen (they changed the SoC specification some weeks ago) thus I wouldn't be surprised to see this slip into 2025. I wouldn't be surprised if this outperforms MilkV Pioneer.
SG2042 itself is T-HEAD C920 design which is a mess, and might not be even called a RISC-V compliant design. We are kinda stuck it existing and being used in various chips. There are other design issues discovered IIRC (atomic might not work properly [at least on the kernel side workarounds required]; floating point failures in glibc testsuite because FP not being compliant). SG2044 is scheduled for the next year (2024). Not many details are known: 64 cores, 8 DDR controller, 3x memory bandwidth, vector v1.0 support, 2x PCIe (unknown what that means, Gen3 -> Gen4? More lanes?). The cores are unknown, but SG2038 is SiFive P670. T-HEAD has C908 that support vectors v1.0 (and solves some other issues), but that's a smaller core. Not a replacement for C910/C920.
StarFive Tech. have been upstreaming on kernel, OpenSBI and U-Boot from several weeks now. Of course this is still weeks/months away (if not more, for all the features) from landing in stable releases. Even more for distributions to pick those up.
There might be gazillions of reason why this was done.
Because it's not ratified the BitManip extensions are not listed in any RISC-V Profiles as supported (or required). Platforms specification is also not requiring it.
Note that the next Profiles will be for 2022, thus any extension ratified before that most likely will appear in a new profile (i.e. as supported, non-conflicting extension) in some set.
The bottleneck here is SoC, not the GPU. With HW decoding on the GPU I can play 4K 60fps trailers on Unmatched just fine.
From https://www.anandtech.com/show/15991/hot-chips-2020-live-blo...
0.7.1 and 1.0 will not be compatible IIRC thus Linux distribution most likely will not support RVV on this.
From whitepaper CSDB is 1101_0101_0000_0011_0010_0010_100_11111
Here some snippets from ARM manuals:
HINT instruction:
1101 0101 0000 0011 0010 0010 100 11111 CRm = 0010 op2 = 100
Some encodings described here are not allocated in this revision of the architecture, and behave as NOPs. (This is important)
Hints 18 to 23 variant Applies when CRm == 0010 && op2 != 00x. HINT #<imm>
Hint is encoded in CRm:op2 pair, existing similar:
0010:000 ESB // Error Synchronization Barrier 0010:001 PSB CSYNC // Profiling Synchronization Barrier
Thus in assembler this is written:
hint #0x14
Which is a NOP if SOC does not understand this hint. It's being used here: http://lkml.iu.edu/hypermail/linux/kernel/1801.0/04191.html
and also here: https://github.com/ARM-software/speculation-barrier/blob/mas... (which is being upstreamed to compilers in cross-platform generic form IIRC)
ARM whitepaper states that conditional selection/conditional move is enough on most ARM implementations. If it's not the case then the new CSDB solves the problem. On older CPUs it's still a NOP.
X-Gene disables branch prediction: http://lkml.iu.edu/hypermail/linux/kernel/1801.2/06482.html
ThunderX2 branch prediction hardening: https://patchwork.kernel.org/patch/10151975/
It's all in ARM Ltd. report and whitepaper.
ABIs have changed after we did this. We get the first long-term stable ABI with 4.15 kernel and glibc 2.27 (hopefully). At that point Fedora, Debian, and others can reboot efforts.