[I am not subscribed to debian-arm.] On Tue, Jan 11, 2005 at 11:03:59PM +0000, Phil Blundell wrote: > On Tue, 2005-01-11 at 12:37 -0500, Branden Robinson wrote: > > Here are his remarks, recast a bit from IRC-speak into something more > > conventional. > > > > GCC on ARM is doing something different from every other C compiler I've > > seen. It may not deviate from what the C specification allows, but it > > appears to deviate from common practice. The ARM folks would find code > > would work with fewer problems if they fixed GCC to behave like other C > > compilers do. Having an array of structs of a byte each usually forces > > 16 bit alignment only on other compilers I've seen. > > Jim is correct. This behaviour of the ARM compiler seemed like a good > idea in 1988, but subsequent experience has shown that it was a mistake > to pad structs in this way. > > Changing the default behaviour of the compiler definitely would result > in ABI breakage for some programs. We plan to take care of this, and a > variety of other historical goofs, by switching to the new ARM "EABI". > This change will involve a flag day at some point during the next Debian > release cycle, but will result in better performance (by a factor of > more than 10 for some code) and greater compatibility with other > architectures. > > > I'm also curious to know if xterm has always had this problem on Debian > > ARM, or if it has cropped up only with recent revisions of GCC. Can anyone > > tell me? > > I don't have any direct experience of the bug, but from the description > I've seen it sounds like it would always have been this way. GCC's > behaviour certainly hasn't changed recently. Since the discussion seems to have died down: I am reaching the conclusion that I'm going to need to apply the patch more or less as written. It can have a lot of #if guards around it, but it sounds like for GNU C and the ARM architecture until this new "EABI" happens[1], this is just something that will have to be done if we want X to work right on Debian/ARM. Jim, do I read this correctly? [1] ...even then it would no doubt have to be kept around for a while, thanks to people not migrating to the new ABI. -- G. Branden Robinson | Those who fail to remember the laws Debian GNU/Linux | of science are condemned to branden@debian.org | rediscover some of the worst ones. http://people.debian.org/~branden/ | -- Harold Gordon
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