Dear Graeme Russ,
Hi Thomas,
P.S. I dropped the DM list...
It took a couple of other emails to get what is going on here...
On 07/29/2012 01:46 AM, Tomas Hlavacek wrote:
Hello!
I am working on early_malloc() for U-Boot Driver Model (this malloc is going to serve for internal DM structures during early init and it has it's minimalistic heap in global data).
Not exactly on-topic, but I really hope that everything is wrapped so a simple call to malloc() will work pre-relocation. Of course, everything you malloc pre-relocation will have to be re-malloc'd and relocated after relocation. Point is, early malloc should not be restricted to the driver framework
My question is how to correctly switch from early allocator to full-scale malloc and when to enable caches.
The current state (on ARM) is:
- gd = id;
- enable_caches();
- mem_malloc_init();
Proposed sequence for mallocator (in order no to loose any data from old and not-relocated part of GD):
- gd_old = gd;
- gd = id;
- mem_malloc_init();
- relocation of DM structures
- early_malloc_disab()
- enable_caches();
I'm thinking:
- Low-level CPU init
- 'Cache-As-RAM' init
- Global Data init
- Pre-console buffer init
Buffer?
- Early malloc() init
- Console init
You don't need console here ... probably, on some systems.
- ...blah, blah, blah...
- SDRAM init
- Relocate Global Data
- malloc() init
- 'Disable' early malloc (i.e. malloc() now allocates from SDRAM)
- Relocate from early_malloc_pool to malloc_pool [1]
- enable_caches()
[1] I'm thinking possibly compile-time registered hooks...
Gurr ... you mean like INIT-something framework?
Does it make sense? It actually boils down to one fundamental question: When I have not-rellocated data locked in cache-lines, do I loose them once enable_caches() is called?
I believe that yes, as soon as you enable caching, everything already in cache (gd, pre-console buffer, early malloc pool etc) is as good as gone
Right ... that's why now it's copied to a safe location alongside other GD (global data)
Regards,
Graeme
Best regards, Marek Vasut