IRC logs for #openrisc Friday, 2013-11-01

--- Log opened Fri Nov 01 00:00:05 2013
stekern_franck_: it usually does :(04:11
olofk_I gave Xilinx and Altera some reprimands for their proprietary debug interfaces on twitter. I'm sure they will stop now after I have told them it's bad!07:37
stekernI would be very surprised if they wouldn't take notice when a member of such a high profile project as openrisc raise their voice of opinion!07:57
olofk_I'm waiting for flowers and a written apology08:16
olofk_Have you heard about the new Stratix 10 btw? It will have a quad core 64 bit ARM. That's pretty insane08:17
stekernI'm not following the high-end fpgas so much08:21
-!- rmarko is now known as impure_hate08:33
-!- Netsplit *.net <-> *.split quits: mick_laptop08:58
rahwhat speed do the FPGA chips run at in the SoCKit?09:04
rahaccording to the "Clock Tree Performance for Cyclone V Device" table in the datasheet, the "Global clock and Regional clock" is 460MHz09:04
rahwhich seems quite good09:04
stekernrah: the question is flawed, so it's hard to answer it09:05
stekernthere is only one fpga chip on the sockit board09:06
rahstekern: how is the question flawed?  is the clock speed variable?09:06
stekernand you can clock different cores at different speed inside the fpga09:06
rahs/in the SoCKit/in the SoCKit boards/09:06
rahI see09:07
stekernand it depends on the core design (and the FPGA) how fast you can clock it09:07
rahwhat effects the clock speed in the core design?09:08
stekernso, to be able to answer your question, you need to have a specific core in mind09:08
stekernhow long combinatorial paths you have (basically)09:09
rahthis is going above my head now09:10
rahwhat kind of clock speeds can you get with an openrisc core?09:10
-!- mick_lap2op is now known as mick_laptop09:38
stekernrah: I haven't pushed it on the sockit, but around 90 MHz without mmu and 75 Mhz with on de0 nano09:59
olofk_Stupid webchat. I thought it was unusally quiet on the channel. Seems I was disconnected10:03
rahstekern: that's quite low :-/10:59
stekernrah: there's room for improvement, but no, it's not very low11:19
stekernI think NiosII, that is optimised for altera can go up to around 150 MHz11:22
stekernon that fpga11:23
stekernand that soc11:25
olofk_I got a MicroBlaze running at 125MHz. Could probably clock it a bit higher, but not much11:42
olofk_stekern: Do you have a feel for the IPC for Nios and MicroBlaze?11:43
rahstekern: I'm comparing it to desktop CPUs11:45
raholofk_: how do you determine whether a clock speed is too high?11:47
rahwhat does "too high" mean? :-)11:48
rahis it a heat issue?11:49
rah(like with desktop CPUs?)11:49
olofk_rah: It's usually not a heat problem. The electrical signals don't have time to reach the next register is the clock is too fast11:52
olofk_But that's the same thing about desktop CPUs. Even if you could cool them, they wouldn't be able to go infinitely fast11:53
raholofk_: I see11:54
stekernolofk_: I think we are up to par with both of them in mor1kx cappuccino11:54
stekernwe beat the coremark/mhz scores for the microblaze results that are published at least, but they were done with a quite old gcc11:55
stekernrah: yeah, it's a well known fact that FPGAs are not very fast, especially not the lowend ones12:05
LoneTecholofk_: that can be a heat problem. higher heat means higher resistance which makes the effective RC filter of signal wire into MOSFET gate slower12:12
LoneTechthis is why overclocking gets easier as you chill things a lot12:12
olofk_I'm off12:26
rahstekern: why kind of speeds could you get with a higher-end FPGA?13:13
rahstekern: I looked at the datasheet for the top-end Stratix V chip, and they quote 717MHz compared to 460MHz in the Cyclone V13:15
rahstekern: would you expect to get an increase in the speed of a processor core, proportional (or thereabouts) to these quoted speeds?13:17
_franck_it's ready:
_franck_please use branch usbblaster217:01
_franck_./configure --enable-usb_blaster_2 --enable-usb_blaster-libftdi --enable-maintainer-mode17:01
_franck_sudo ./src/openocd -f ./tcl/interface/altera-usb-blaster.cfg -f ./tcl/board/or1k_sockit.cfg -s ./tcl17:01
_franck_and tell me if it works for you....17:01
--- Log closed Sat Nov 02 00:00:06 2013

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