Yann Sionneau <y...@minet.net> schrieb:
>I just copy pasted Milkymist MMU documentation on github wiki : >https://github.com/fallen/milkymist-mmu/wiki > From now on I will update this one with more and more informations >about the current MMU implementation/specifications > >Le 09/07/2012 12:04, Werner Almesberger a écrit : >> Yann Sionneau wrote: >>> *TLB size : 1024 entries >> 1024+1024 is pretty big. I found Longsoon 2E has 16+64 [1], Itanic >> has 96+128, PowerPC 405 has 64 (unified ?) [3], only Intel i7 comes >> somewhat close with 576 entries per core. [4] >Indeed it's pretty big, I think we still have a lot of unused resources > >in the Spartan-6 FPGA so it's not a problem if I use a lot of BlockRAM. >Anyway the size of the TLB can be changed pretty easily in the Verilog >code, there is a parameter called "dtlb_sets" (or itlb_sets) which >contains 1024 for now. > >I agree we may have to do some benchmarking to chose wisely the more >adapted value :) >> >> [1] >http://www.datasheetarchive.com/STLS2E02/Datasheet-045/DSA0019307.html >> [2] http://www.informit.com/articles/article.aspx?p=29961&seqNum=4 >> [3] http://www.xilinx.com/ipcenter/processor_central/embedded/mmu.htm >> [4] >http://www.lostcircuits.com/mambo//index.php?option=com_content&task=view&id=31&Itemid=1&limit=1&limitstart=4 >> >>> - 5'h4 : Switch to kernel mode (for debugging and developpment >purposes only, >>> will be removed later on) >>> - 5'h8 : Switch to user mode (for debugging and developpment >purposes only, >>> will be removed later on) >> When these are removed, how do you switch between user and kernel >mode ? >Upon any exception, both TLB are going into "kernel mode". >Upon "eret" (return from exception) both TLB are going into "user >mode". > >I should change the name of those modes, "kernel" and "user" does not >reflect the real thing. >Because Linux kernel will run in "user mode". in user mode? the mmu will be enabled if the kernel is running? -- Michael _______________________________________________ http://lists.milkymist.org/listinfo.cgi/devel-milkymist.org IRC: #milkymist@Freenode
