[U-Boot] a couple questions about CONFIG_SYS_LONGHELP

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hi Robert,

On Sat, 26 Jan 2013 07:11:18 -0500 (EST), "Robert P. J. Day"
<rpjday@crashcourse.ca> wrote:

> On Sat, 26 Jan 2013, Albert ARIBAUD wrote:
> 
> > Hi Robert,
> >
> > On Sat, 26 Jan 2013 06:38:51 -0500 (EST), "Robert P. J. Day"
> > <rpjday@crashcourse.ca> wrote:
> 
> ... snip ...
> 
> > >   and second, i'm not sure how to read this out of cmd_pci.c:
> > >
> > > ===== start
> > >
> > > #ifdef CONFIG_SYS_LONGHELP
> > > static char pci_help_text[] =
> > >         "[bus] [long]\n"
> > >         "    - short or long list of PCI devices on bus 'bus'\n"
> > > #ifdef CONFIG_CMD_PCI_ENUM
> > >         "pci enum\n"
> > >         "    - re-enumerate PCI buses\n"
> > > #endif
> > >         "pci header b.d.f\n"
> > >         "    - show header of PCI device 'bus.device.function'\n"
> > >         "pci display[.b, .w, .l] b.d.f [address] [# of objects]\n"
> > >         "    - display PCI configuration space (CFG)\n"
> > >         "pci next[.b, .w, .l] b.d.f address\n"
> > >         "    - modify, read and keep CFG address\n"
> > >         "pci modify[.b, .w, .l] b.d.f address\n"
> > >         "    -  modify, auto increment CFG address\n"
> > >         "pci write[.b, .w, .l] b.d.f address value\n"
> > >         "    - write to CFG address";
> > > #endif
> > >
> > > U_BOOT_CMD(
> > >         pci,    5,      1,      do_pci,
> > >         "list and access PCI Configuration Space", pci_help_text
> > > );
> > >
> > > ===== end
> > >
> > >   note how, if CONFIG_SYS_LONGHELP is defined, the symbol
> > > "pci_help_text" is created as the text, but its *usage* just below in
> > > the U_BOOT_CMD macro is *outside* of that preprocessor check.  how
> > > would that work if CONFIG_SYS_LONGHELP is undefined?  not at my dev
> > > host right this minute so i can't test, but it just looks ... weird.
> >
> > Probably would not work. Submit a fix. :)
> 
>   there appears to be a number of common/cmd_*.c files that have that
> structure:
> 
> $ grep "ifdef.*CONFIG_SYS_LONGHELP" cmd*.c
> cmd_bootm.c:#ifdef CONFIG_SYS_LONGHELP
> cmd_bootm.c:#ifdef CONFIG_SYS_LONGHELP
> cmd_fdt.c:#ifdef CONFIG_SYS_LONGHELP
> cmd_help.c:#ifdef  CONFIG_SYS_LONGHELP
> cmd_i2c.c:#ifdef CONFIG_SYS_LONGHELP
> cmd_mp.c:#ifdef CONFIG_SYS_LONGHELP
> cmd_mtdparts.c:#ifdef CONFIG_SYS_LONGHELP
> cmd_nand.c:#ifdef CONFIG_SYS_LONGHELP
> cmd_nvedit.c:#ifdef CONFIG_SYS_LONGHELP
> cmd_pci.c:#ifdef CONFIG_SYS_LONGHELP
> cmd_source.c:#ifdef CONFIG_SYS_LONGHELP
> cmd_ximg.c:#ifdef CONFIG_SYS_LONGHELP
> $
> 
>   so it's not just one file.

The grep above just shows that there are files have conditionally
compiled code for CONFIG_SYS_LONGHELP; however it does not show per
se that these files wound not compile without it.

Even assuming some of these files would not build without
CONFIG_SYS_LONGHELP (cmd_pci.c is already proven not to), at least for
ARM (an architecture for which I frequently build all targets) no
target fails with an undefined variable, which implies that no target
uses any of those files without defining CONFIG_SYS_LONGHELP.

My conclusion is: if you need to build one or more targets without
CONFIG_SYS_LONGHELP and it fails in some cmd_*.c file, then submit a
patch that fixes the cmd_*.c files and undefines CONFIG_SYS_LONGHELP
in the include/configs/*.h header files for those targets.

> rday

Amicalement,
-- 
Albert.