Re: [Qemu-devel] [PATCH, RFC] Smarter compilation for target devices

[Blue Swirl <blauwirbel@gmail.com>]

On 4/28/09, Paul Brook <paul@codesourcery.com> wrote:
> > Compile target devices only once for each endian and word size combination,
>  > saving a few compiles if large number of targets are enabled.
>
>
> > +CPPFLAGS=-I. -I.. -I$(SRC_PATH) -MMD -MT $@ -MP -DNEED_CPU_H
>
>
> > +# Warning: Do not add new files here if they have conditional code
>  > +# with #ifdef TARGET_xxx etc, use TARGET_PAGE_SIZE or reference
>  > +# CPUState
>
>
> This is just asking for trouble. Anything that includes cpu.h must be rebuilt
>  for every cpu.  IMO a necessary prerequisite for this change is reworking
>  header files so that you can't accidentally use the wrong symbols.

Yes, this was a hack. I think with your header change it will be much cleaner.

>  Also, which bitwidth are you intending to distinguish here? target_ulong or
>  target_phys_addr_t? With a few exceptions, devices don't care about the

target_phys_addr_t, of course. The devices that know about
target_ulong (or CPUState, TARGET_PAGE_SIZE) can't use this system.

>  former. Duplicating this logic is both cpu.h and configure is also asking for
>  trouble. At minimum the build should fail if they disagree.

Which logic?