On Fri, Nov 6, 2009 at 6:44 PM, David Daney <ddaney@xxxxxxxxxxxxxxxxxx> wrote: > Dmitri Vorobiev wrote: >> >> On Fri, Nov 6, 2009 at 6:22 PM, Dmitri Vorobiev >> <dmitri.vorobiev@xxxxxxxxx> wrote: >>> >>> On Fri, Nov 6, 2009 at 6:08 PM, Atsushi Nemoto <anemo@xxxxxxxxxxxxx> >>> wrote: >>>> >>>> Recently COMMAND_LINE_SIZE (CL_SIZE) was extended to 4096 from 512. >>>> (commit 22242681 "MIPS: Extend COMMAND_LINE_SIZE") >>>> >>>> This cause warning if something like buf[CL_SIZE] was declared as a >>>> local variable, for example in prom_init_cmdline() on some platforms. >>>> >>>> And since many Makefiles in arch/mips enables -Werror, this cause >>>> build failure. >>>> >>>> How can we avoid this error? >>>> >>>> - do not use local array? (but dynamic allocation cannot be used in >>>> such an early stage. static array?) >>> >>> Maybe a static array marked with __initdata? >> >> Also, I just thought that maybe it's possible to use a c99 >> variable-length array here? Like this: >> >> int n = COMMAND_LINE_SIZE; >> char buf[n]; >> >> This way, we don't put yet another variable in the .init.data section, >> unlike with the static array solution. >> >> However, this is totally untested, just a thought... >> > > It depends on your concerns. You are still using 4096 bytes of stack, but > you are trying to trick the compiler into not warning. > > If you think the warning is bogus, you should remove it for all code, not > just this file. If you think the warning is valid, then you should fix the > code so that it doesn't use as much stack space. Frankly, I don't think that the warning is bogus, especially if we're talking about the case of the 4K page and 32-bit kernel, and I started thinking htat probably the static array solution would be the safest bet here. Dmitri
