-----Original Message----- From: Mandeep Sandhu [mailto:Mandeep_Sandhu@xxxxxxxxxxx] Sent: Wednesday, October 06, 2004 4:03 PM To: jonathan@xxxxxxxxxxxxxx Cc: Thekkedath, Gopakumar; ruxyz@xxxxxxxxx; Thekkedath, Gopakumar; Omanakuttan; Ribamar Santarosa de Sousa; Kernel Newbas. Subject: Re: RAM or "empty"? >I had read somewhere that accessing IO ports thru. MMIO is faster >than thru. IO-maped-IO? any pointers as to why this would be??? >wud'nt MMIO access's have the extra overhead of address translation >from vir. -> phy ??? If i use PIO (x86 arch.) shud'nt the access >be faster as here i have special instr. for this purpose...or is >that these instr. themselves r slow...i.e they take more clk cycles >to complete??? I don't think in I/O maped IO is slower than memory mapped I/O(correct me if i am wrong). One constraint with the I/O mapping in x86 machines are that their address space is only 64KB as they use only 16 address lines. Any further inputs are welcome gop -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
