On 4/3/21 5:53 pm, Sebastian Huber wrote: > On 04/03/2021 00:18, Chris Johns wrote: >> On 3/3/21 7:48 pm, Sebastian Huber wrote: >>> On 03/03/2021 08:52, Chris Johns wrote: >>>> Then I hit minimum and some validation tests and they failed because I had >>>> removed bsp/default-initial-extension.h and I suppose it needs to come via >>>> bsp.h >>>> however it includes rtems.h because it needs to have access to >>>> rtems_fatal_source etc. >>>> >>>> It seems there is a lot of places that subtly depend on bsp.h and what it >>>> includes. >>>> >>>> I will chat to Joel tomorrow to figure out how this is to be resolved. >>>> >>>> Any suggestions? >>> The minimum requirement for bsp.h is to include: >>> >>> rtems.h >>> >>> bspopts.h >> It is news to me this is a requirement and I am unsure where it has come >> from. >> Has it been documented? The information you cut from my last post shows >> RTEMS is >> pretty clean and the number of issues are small so I am not sure this needs >> to >> happen. > This is what I figured out over the years.
I think the ability to have them separated is healthy. >> >> These powerpc BSPs predate libbsd, they have legacy networking support and >> are >> important to RTEMS users. >> >> Your request to not including bsp.h because it includes rtems.h in a driver >> section of a third party package that needs specific BSP bus mapping >> information >> appear to conflict. The package needs low level BSP information but it cannot >> include bsp.h by definition now. >> >> What is now bugging me is the layering of rule upon rule mixed with defaults. >> The rules are complex and in places seem arbitrary. Let me write the rules >> out >> as I understand them: >> >> 1. The BSP header bsp.h is the access to BSP interfaces >> >> 2. The BSP header bsp.h must include rtems.h and bspopt.h >> >> 3. LibBSD generic bus handling must be inline for performance reasons >> >> 4. LibBSD generic bus handling assumes cache coherent memory by default >> >> 5. BSPs must register cache coherent memory if it does not meet rule 4 >> >> 6. LibBSD generic bus handling defaults to a flat 1:1 full memory space >> address map >> >> 7. LibBSD generic bus handling requires bsp/bus.h to provide BSP mappings >> if it does not meet rule 6 >> >> 8. A BSP provided bsp/bus.h cannot include rtems.h or any header that >> includes rtems.h such as bsp.h. This special case is exempt from rule 1 >> >> 9. RTEMS cannot change any header an existing BSP with bsp/bus.h >> includes to include rtems.h or any header that has a dependent that >> includes rtems.h >> >> <bleach> that is a lot of rules to swallow. An alternative set of rules is: >> >> 1. The BSP header bsp.h is the access to BSP interfaces >> >> 2. LibBSD generic bus handling must be inline for performance reasons >> >> 3. LibBSD generic bus handling requires a BSP provide suitable cache >> coherent memory to the cache coherent memory allocator >> >> 4. LibBSD generic bus handling requires a BSP provide bsp/bus.h to >> provide BSP IO mappings >> >> The second set of rules is clear, does not self reference and universally >> applies to all BSPs. It removes the defaults from LibBSD and lets us manage >> them >> in rtems.git for a BSP. Explicitly requiring a BSP to provide support lets a >> user easily check any BSP to see what cache coherent memory is configured and >> what the bus handlers are. >> >>> It shall also define BSP_INITIAL_EXTENSION (normally via #include >>> <bsp/default-initial-extension.h>). >> This is a recent addition and it is the only piece I found that has an issue >> when building the motorola_powerpc. Maybe the way this is implemented is >> needs >> to be reconsidered or we accept bsp.h does include rtems.h either directly or >> indirectly. >> >> The ability to interchange either bsp.h or rtems.h or having code that >> depends >> on one because you include the other seems wrong. > > We should move away from BSP-specific interfaces. Could you please expand a little on this? I am wondering how "interfaces" is being use here. Would a bsp/bus.h interface based on the macros I listed in this thread's patch work as a start? I have isolated around 5 powerpc BSPs that would need to be updated as a set... beatnik psim motorola_powerpc mvme5500 haleakala I plan to discuss this tomorrow with Jennifer and Kinsey to figure out how to resolve this. Your input and feedback has been valuable. > The <bsp.h> is the only > mandatory header file provided by a BSP and may contain all sorts of things. Yes it is a bit of a sweeper for a lot of things, a little too much. > From my point of view the BSP should indicate which features it > requires/supports and then it should implement a standard interface. That would be nice. There are defacto standards in some parts where driver sharing required it happen but I think there is no uniform set of interfaces. A key issue is the size of a task that needs to touch all BSPs. We tend to look at blocks of work in the generic areas or as a specific BSP or family of BSPs. Large refactoring of BSPs is hard to get funding for and hard to test. > The bus API implementation in FreeBSD is architecture-specific. It is and I am fine with how we currently have thing implemented in libbsd. The x86 needs its own bus API and I reviewed the rtemsbsd shared bus support and it currently fits most cases I can see. I wondered about a powerpc specific bus version and all I would end up doing is the same thing we have in rtemsbsd plus something like the patch in this thread. I also reviewed the FreeBSD implementation for the powerpc, we should avoid it. > We can do this in RTEMS as > well and do the implementation in cpukit, for example based on the riscv > implementation in FreeBSD. The BSP could then simply indicate if it needs a > full > featured implementation or the simple inline implementation we have currently. Yeah this sound nice. > The definition of BSP_INITIAL_EXTENSION can move to a separate header file. I wonder about this but I could not see how to implement it. > The cache coherent memory is a different topic and I think this is already > sorted out in > > http://devel.rtems.org/ticket/4243 Yes and I hopefully have an elegant solution in mind for those BSPs who currently depend on the default heap allocation. I included it here to make the list of rules as complete as possible to avoid the post appearing in searches and being confused as "the" list. Chris _______________________________________________ devel mailing list devel@rtems.org http://lists.rtems.org/mailman/listinfo/devel
