Hi, On Mon, Nov 22, 2010 at 9:32 PM, Luis R. Rodriguez <lrodriguez@xxxxxxxxxxx> wrote: > On Mon, Nov 22, 2010 at 6:19 PM, Arnaud Lacombe <lacombar@xxxxxxxxx> wrote: >> Hi, >> >> On Mon, Nov 22, 2010 at 1:09 PM, Luis R. Rodriguez >> <lrodriguez@xxxxxxxxxxx> wrote: >>> On Sun, Nov 21, 2010 at 5:36 PM, Arnaud Lacombe <lacombar@xxxxxxxxx> wrote: >>>> [...] >>>> The compat headers should be at the end of the include list, so that >>>> the kernel headers get included first, and the compat one will only be >>>> when the kernel does not provide the header. This is the only sane way >>>> to override kernel provided stuff. That said, there is certainly a >>>> use-case I missed. >>> >>> Agreed, but you are missing the purpose of the trick used here. >> certainly :) >> >>> The >>> purpose of the include_next was so that we can name our own >>> <linux/pm_qos_params.h> which is part of compat and these directories >>> *will* get a priority over the kernel's so that way we can avoid >>> ifdef'ing all includes for the same file on the upstream code. >> I'm not sure to get what you mean by "we can avoid ifdef'ing all >> includes for the same file on the upstream code", can you details ? > > Ah, that's right, you don't see or use compat-wireless likely. Ok, so > what we do for backporting the 802.11 subsystem, Bluetooth and some > Ethernet drivers is we take the stock upstream files, stuff them into > a new directory, and then apply a series of patches to them to get the > files to properly compile. The patches address all things that was not > possible to backport through compat.git. Header file changes is one of > the typical things we run into. If a new header file is added to newer > kernels we can play a hack for older kernels and leave the code intact > and introduce our own include/linux/foo.h through compat by prefering > the local path over the kernel's path. If we're on newer kernels > though include_next will go on the search path and find the kernel's > own header file. > Is there any reason you want the compat's include directory to be *before* the kernel include directory ? Because just considering this issue, if the kernel include directory was seen first, this would not arise, as the compat-provided header would just be a fallback. - Arnaud -- To unsubscribe from this list: send the line "unsubscribe linux-wireless" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
