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====== Joshua Oreman: 802.11 wireless development ====== ===== Journal Week 9 ===== ==== Tuesday, 21 July ==== I'm back! Trip was a lot of fun, but I'm glad to be back working on gPXE. I spent a bit of time today getting my code up to date with the changes that have been made on gPXE mainline while I was away. The effect of this is a new mainline-review branch with its three core pending wireless commits slightly modified, and a merge commit on the wireless branch. I also started working on the device firmware loading we discussed in my last weekly meeting before I left. The problem is not at all complicated and I expect to have it done by early tomorrow. ==== Wednesday, 22 July ==== Firmware loading is done and tested with a trivial application. (I don't own any cards supported by gPXE that actually require firmware.) * On new branch **firmware**: * [[http://git.etherboot.org/?p=people/oremanj/gpxe.git;a=commit;h=1fd2f4627d2e4e7ea8f5b2c1d9e9b5aff65e4ab3| [embedded] Add support for multiple sources and types of embedded images]] * [[http://git.etherboot.org/?p=people/oremanj/gpxe.git;a=commit;h=95331202fa7ecbe878c71e0cf45514012c5cabb3| [image] Add support for device firmware images]] A device needing firmware declares that dependency using a ''REQUIRE_FIRMWARE()'' or ''USE_FIRMWARE()'' macro, where ''REQUIRE'' is meant to have the semantics that a link without the firmware file available will fail. Depending on the architecture this may not always be the case (it simply uses the underlying ''REQUIRE_OBJECT()'' macro defined in ''compiler.h''). It gets at the firmware data using a function ''request_firmware()''. I have modified the build system so that any file in the ''src/firmware/'' directory whose name does not start with ''README'' will automatically be compiled in as an embedded image if another compiled-image object uses ''REQUIRE_FIRMWARE()'' or ''USE_FIRMWARE()'' to pull it in. Currently ''USE_FIRMWARE()'' is implemented rather uglily, by adding a Perl script that searches for ''USE_FIRMWARE()'' uses and creates a linker script to provide dummy symbols preventing a link error only if the used firmware is not available at link-time. I have found in my testing that ''REQUIRE_FIRMWARE()'' does not actually introduce a strong dependency, so that on x86 at least the two are equivalent and there is no need for the Perl script ugliness. I am not sure whether this is a portable assumption, but since ''REQUIRE_OBJECT()'' works by producing a symbol reference without ever using the symbol value, it may be. If so the situation can be rather simplified---take out ''REQUIRE_FIRMWARE()'' entirely, and the ''fwfix.pl'' Perl script as well.
