configure: extend some config variable descriptions.

* configure: Add some help text for variables controllinig the
compiler command. Mention that CFLAGS and LDFLAGS are honored
from the environment or make command line on top of any of the
flags settable here.

1 files changed, 11 insertions, 2 deletions

diff --git a/configure b/configure
index 8194bfa7..8f05b690 100755
--- a/configure
+++ b/configure
@@ -291,6 +291,8 @@ cross [$cross]
   default will be added as a prefix to all of the toolchain commands.
   It should include the trailing slash, unless the \$compiler_prefix
   and \$tool_prefix variables take care of this by providing a leading slash.
+  If this variable is set, ccname should also be set; the default
+  ccname doesn't make sense in that case.
 
 compiler-prefix [$compiler_prefix]
 
@@ -300,17 +302,22 @@ compiler-prefix [$compiler_prefix]
   \$cross is "/cross/toolchain/" and \$compiler_prefix is
   "bin/mips-linux-" then the compiler command, unless otherwise
   specified, will be "/cross/toolchain/bin/mips-linux-gcc".
+  If this variable is set, ccname should also be set; the default
+  ccname doesn't make sense in that case.
 
 ccname [$ccname]
 
   Specifies just the name of the compiler front-end program, without the path.
   The following variable, cc, specifies the full name.
+  The default value is the \$(CC) predefined make variable.
 
 cc [$cc]
 
   Specifies the name of the toolchain front-end driver command to use for
   compiling C sources to object files, and for linking object files to
   executables. This becomes the TXR_CC variable in config.make.
+  Note that cross and compiler_prefix are empty by default and
+  and so this expands to just ccname.
 
 intptr [$intptr]
 
@@ -369,7 +376,8 @@ nm [$nm]
 opt-flags [$opt_flags]
 
   Specifies optimization flags to use for compiling and linking
-  C sources.
+  C sources. Note that these are in addition to any CFLAGS
+  passed in the environment or on the make command line.
 
 lang-flags [$lang_flags]
 
@@ -407,7 +415,8 @@ platform-cflags [$platform_cflags]
 platform-ldflags [$platform_ldflags]
 
   Specify additional linker flags for anything else, such as hardening,
-  linking as needed, et cetera.
+  linking as needed, et cetera. Note that these are in addition to
+  any LDFLAGS from the environment or make command line.
 
 remove-flags [$remove_flags]