Hello Trent, On 14.09.21 21:11, Trent Piepho wrote: > On Tue, Sep 14, 2021 at 6:21 AM Ahmad Fatoum <a.fatoum@xxxxxxxxxxxxxx> wrote: >> >> We currently build the USB loader tools only for the host (build) system, >> but it can be useful to cross compile them as well for the target. >> >> We already have some target tools, but support for those is easier, >> because they don't link against libraries. We use pkg-config to get >> cc and ld flags, but we always assume that pkg-config is for the host >> system and there is no well-defined way to request pkg-config for the >> target system. >> >> Support this by introducing a new CROSS_PKG_CONFIG. This will be >> consulted only for target tools and default to >> $(CROSS_COMPILE)pkgconfig. >> >> Users can override it as necessary, for example, with Yocto, pkg-config >> will be for the cross environment, so target tools can now be built >> with: > > I just added support to Buildroot for building imx-usb-loader from > Barebox, since it's nicer than the standalone version of the program. > > Since pkgconfig was only used for host tools, I didn't need to make > both host and target pkgconfig work. But of course that will no > longer be true after this patch. It still wouldn't break your workflow, imx-usb-loader wasn't built for target so far. > There is a problem with only supplying CROSS_PKG_CONFIG. To get both > host and target pkgconfig to work, I also need to supply the env > variables used by pkgconfig, PKG_CONFIG_SYSROOT and PKG_CONFIG_LIBDIR. You can set these on the environment before starting barebox build. If you have a $(CROSS_COMPILE)pkg-config that doesn't need any further configuration, you can use that. > The former makes the paths returned by pkgconfig correct and the > latter controls which set, target or host, of .pc files will be used. > > Maybe something like this in the Makefile: > > CROSS_PKG_CONFIG ?= $(CROSS_COMPILE)pkg-config > CROSS_PKG_CONFIG_SYSROOT ?= $(PKG_CONFIG_SYSROOT) > CROSS_PKG_CONFIG_LIBDIR ?= $(PKG_CONFIG_LIBDIR) > CROSS_PKG_CONFIG_ENV := \ > PKG_CONFIG_LIBDIR=$(CROSS_PKG_CONFIG_LIBDIR) \ > PKG_CONFIG_SYSROOT=$(CROSS_PKG_CONFIG_SYSROOT) > > HOST_LIBUSB_CFLAGS := $(shell $(PKG_CONFIG) --cflags) > CROSS_LIBUSB_CFLAGS := $(shell $(CROSS_PKG_CONFIG_ENV) > $(CROSS_PKG_CONFIG) --cflags) > > Then use those everywhere someone wants the libusb cflags. Repeat for LDFLAGS. I am not really sold on this. Linux doesn't mess with PKG_CONFIG_ variables either. For perf the assume $(CROSS_COMPILE)pkg-config to be available. I think it's a suitbale default for us too. The lines above can go into a shell script wrapper. > You'll get fewer repeated invocations of pkg-config this way too. Ye, I thought about that as well, but we do it like this for the host tools, so I left it for now. It's not much overhead and it makes it a bit easier to follow what is used. Cheers, Ahmad -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 | _______________________________________________ barebox mailing list barebox@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/barebox
