Da Zheng, le Sat 24 Apr 2010 18:29:50 +0800, a écrit : > On 10-4-23 下午7:37, Samuel Thibault wrote: > > Da Zheng, le Fri 23 Apr 2010 14:51:22 +0800, a écrit : > >> They are not just one or two variables. They are an array of structure > >> variables. Should I define all fields of the structure with volatile > >> qualifier? > > > > You can qualify the whole structure > > > >> It's strange. The Linux driver doesn't do so but it definitely works in the > >> Linux kernel. > > > > It does (or should do): such pointers have the __io qualifier. > I checked the code of e1000 again. The data for MMIO is qualified by __iomem,
Right, I hadn't checked the precise name :) > but the data in the transmission or receiving queues (which are accessed by > DMA) > doesn't have __iomem or any similar qualifiers. Because they are only accessed by DMA, aren't they? > I guess the data in the transmission queue is very unlikely to be in > registers when the driver accesses it. You said yourself that DMAs take care of cache coherency :) (and I indeed guess they do). Samuel
