Kernel compilation flags – A pain in the a*

So I pulled snq’s froyo kernel (that guy is a marvel)..

Some kernel compilation errors:

1. Treat warnings as errors-Solved by removing the string “-Werror” from all Makefiles of the file which failed to compile. Some people had said that the real error (Array out of bounds warning) was because of gcc optimizations. But putting -O2 to -O0 didnt do a thing. This can also be done from menuconfig: System type>Force warnings as errors
2. No of jobs – ought not to exceed 50.
3. “warning: variable set but not used [-Wunused-but-set-variable]”-Look at KBUILD_CFLAGS in the main Makefile. Add -Wno-unused-but-set-variable to the existing set of flags. You can alternately add a line that says

Note the following from gcc manual:

Refer Preprocessor options

• -Werror[/code]Make all warnings into hard errors. Source code which triggers warnings will be rejected.

• -w[/code]Inhibit all warning messages.

• -Werror[/code]Make all warnings into errors.

• -Werror=[/code]Make the specified warning into an error. The specifier for a warning is appended, for example -Werror=switch turns the warnings controlled by -Wswitch into errors. This switch takes a negative form, to be used to negate -Werror for specific warnings, for example -Wno-error=switch makes -Wswitch warnings not be errors, even when -Werror is in effect. You can use the -fdiagnostics-show-option option to have each controllable warning amended with the option which controls it, to determine what to use with this option.

Though the -Wunused-but-set-variable is not a real issue in itself, it generates so much "noise" that you may miss actual make errors.

This is what I was talking about in No 1.

drivers/net/wireless/bcm4329_204/wl_iw.c: In function 'wl_iw_set_pmksa':

drivers/net/wireless/bcm4329_204/wl_iw.c:5075:5: error: array subscript is above array bounds [-Werror=array-bounds]

drivers/net/wireless/bcm4329_204/wl_iw.c:5078:5: error: array subscript is above array bounds [-Werror=array-bounds]

[/code]

Solution:

Edit drivers/net/wireless/bcm4329_204/Makefile
Locate -Werror within DHDCFLAGS, and delete it.
DHDCFLAGS = -DLINUX -DBCMDRIVER -DBCMDONGLEHOST -DDHDTHREAD -DBCMWPA2

-DUNRELEASEDCHIP -Dlinux -DDHD_SDALIGN=64 -DMAX_HDR_READ=64

-DDHD_FIRSTREAD=64 -DDHD_GPL -DDHD_SCHED -DBDC -DTOE -DDHD_BCMEVENTS

-DSHOW_EVENTS -DBCMSDIO -DDHD_GPL -DBCMLXSDMMC -DBCMPLATFORM_BUS

-Wall -Wstrict-prototypes -Werror -DOOB_INTR_ONLY -DCUSTOMER_HW2

-DDHD_USE_STATIC_BUF -DMMC_SDIO_ABORT -DWLAN_PFN -DWLAN_PROTECT

-DBCMWAPI_WPI

[/code]

This will prevent gcc from treating mere warnings as errors.
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