On Tue, May 14, 2013 at 3:15 PM, Tom Rini <tr...@ti.com> wrote: > On Tue, May 14, 2013 at 02:27:32PM -0700, Simon Glass wrote: >> Hi Tom, >> >> On Tue, May 14, 2013 at 2:21 PM, Tom Rini <tr...@ti.com> wrote: >> > On Mon, May 13, 2013 at 03:12:07PM -0700, Simon Glass wrote: >> >> Hi Tom, >> >> >> >> On Thu, Mar 21, 2013 at 7:38 AM, Tom Rini <tr...@ti.com> wrote: >> >> > On Tue, Feb 26, 2013 at 08:10:53AM -0800, Simon Glass wrote: >> >> > >> >> >> Many parts of the U-Boot code base are sprinkled with #ifdefs. This >> >> >> makes >> >> >> different boards compile different versions of the source code, meaning >> >> >> that we must build all boards to check for failures. It is easy to >> >> >> misspell >> >> >> an #ifdef and there is not as much checking of this by the compiler. >> >> >> Multiple >> >> >> dependent #ifdefs are harder to do than with if..then..else. Variable >> >> >> declarations must be #idefed as well as the code that uses them, often >> >> >> much >> >> >> later in the file/function. #ifdef indents don't match code indents and >> >> >> have their own separate indent feature. Overall, excessive use of #idef >> >> >> hurts readability and makes the code harder to modify and refactor. For >> >> >> people coming newly into the code base, #ifdefs can be a big barrier. >> >> >> >> >> >> The use of #ifdef in U-Boot has possibly got a little out of hand. In >> >> >> an >> >> >> attempt to turn the tide, this series includes a patch which provides >> >> >> a way >> >> >> to make CONFIG macros available to C code without using the >> >> >> preprocessor. >> >> >> This makes it possible to use standard C conditional features such as >> >> >> if/then instead of #ifdef. A README update exhorts compliance. >> >> > >> >> > OK, this is true. Looking over the series, a number of the patches are >> >> > just general fixes / improvements that don't depend on the autoconf_... >> >> > work. Lets split this out now and take them in now as they seem like >> >> > reviewable by inspection code. >> >> >> >> Well sorry I didn't make time to get this done last time. I can do >> >> this now or... >> >> >> >> > >> >> > For the approach itself, I'm not sure which is best here. In a lot of >> >> > cases we're trading an #ifdef for adding a level of indent to already >> >> > pretty indented code and that feels like a wash, in terms of readability >> >> > to me. We probably need to re-factor some of the code in question there >> >> > too for readability, then see about using autoconf_... type things, or >> >> > maybe something else. >> >> >> >> I think you are saying to do the rearrangement and clean-up first, >> >> then add autoconf afterwards. I can do that but really I am wondering >> >> what you think of the autoconf concept? The Kconfig stuff is related >> >> here too, but first I would like to decide on what to do with the >> >> #ifdefs. >> > >> > I think a lot of our #ifdefery is a problem of code that's in need of >> > some love and re-org and cleaning and updating. One of the old style >> > rules I still try and follow is that after a few levels of indent code >> > doesn't read well. Also big nested #ifdefs don't read well. So we're >> > trading one in for the other. But your series showed a lot of places >> > where we can re-factor things to improve readability. So lets go that >> > way. Then we can see if there's still things to improve on, and what >> > dead code we still have around. >> >> So are you saying that you are keen on the autoconf idea? > > I'm saying lets clean up the code and see if we still need something > like autoconf. It seems to provide the most benefit in terms of > readability in places that could read a lot better with some clean up > and refactoring before we add new tools to the pile. >
Yet another great advantage of autoconf is that it ensures a consistent combination of the configuration options, with the status quo it is so easy to make a mistake and create a deficient configuration. --vb > -- > Tom _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
