when to switch from early_ioremap to ioremap

To obtain an address to a PFN in init_hypervisor_platform (called from arch/x86/kernel/setup.c:setup_arch) I use early_ioremap. Later the address to that PFN needs to be obtained with ioremap, and early_iounmap needs to be called on the first address.

When is the time to obtain and use the new pointer, and to release to old pointer? Right now I do that in the pci-device setup code, which happens to work. Unfortunately early_ioremap is not mentioned in Documentation/, hence the question.

Olaf

usually early_ioremap is used in this way:
map it and check it and unmap it. and some time you could back up it before unmap.

you should only use early_iomap and early_memmap during SYSTEM_BOOTING

and check_early_ioremap_leak in late_initcall will check if all early one get unmapped.

for 32bit, there is more requirement: you can not cross init_memory_mapping.
early_ioremap_page_table_range_init/early_ioremap_reset will be
called in init_memory_mapping.

Also early_ioremap has slot limitation: 4. and you should not hold one slot too long, otherwise other users could
have problem to reach the limit.

Yinghai

Thanks. After which init call is ioremap available anymway?

Olaf

after mm_init