Messages in this thread | | | Date | Fri, 11 Nov 2011 12:14:13 -0600 | From | Larry Finger <> | Subject | nommu warning message |
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For the driver rtl8192cu (a USB wireless device), the current version loads the 15KB firmware asynchronously one 32-bit quantity at a time. Although inefficient. this method works with USB 1.1 and USB 2.0 adapters; however, it fails on at least one USB 3.0 adapter with "xhci_hcd 0000:05:00.0: ERROR no room on ep ring" errors.
These errors are believed to arise from small, fixed-size ep rings. There is a vendor driver that works with that same hardware. The major difference is that it uses synchronous block writes of 254 bytes. When I tried this with the in-kernel driver, each block write yields a warning as shown below:
nommu_map_single: overflow 41000340d020+254 of device mask ffffffff
The only remaining difference between the two drivers is that the vendor version uses firmware hard coded into the driver while the kernel version uses a file from /lib/firmware.
My cpu info is:
----- /proc/cpuinfo ----- processor : 0 vendor_id : AuthenticAMD cpu family : 15 model : 104 model name : AMD Turion(tm) 64 X2 TL-60 stepping : 2 cpu MHz : 2000.000 cache size : 512 KB physical id : 0 siblings : 2 core id : 0 cpu cores : 2 apicid : 0 initial apicid : 0 fpu : yes fpu_exception : yes cpuid level : 1 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow rep_good nopl extd_apicid pni cx16 lahf_lm cmp_legacy svm extapic cr8_legacy 3dnowprefetch lbrv bogomips : 4001.06 TLB size : 1024 4K pages clflush size : 64 cache_alignment : 64 address sizes : 40 bits physical, 48 bits virtual power management: ts fid vid ttp tm stc 100mhzsteps
Could someone please explain the meaning of the above messages? Even with them present, the device works.
Thanks,
Larry
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