Re: [PATCH 1/2] OLPC: Add support for calling into Open Firmware

From: H. Peter Anvin
Date: Mon Apr 21 2008 - 09:33:53 EST


Okay, stepping back a few steps, it's pretty clear that most of my objections aren't really an issue for Geode/OLPC; however, I *really* don't want others to pick it up as being "the" Open Firmware interface.

Within those constraints it makes sense to set up the PDEs in swapper_pg_dir and let them propagate using the normal mechanisms.

** This is assuming that your OF interface does not rely on a 1:1 mapping of low memory being present at the time it makes a call. If it *does*, then a separate page directory needs to be maintained for the OF class. **


Thus, I'm willing to accept this with these changes:

- Please name things specific to the interface (as opposed to Open Firmware in general, like the device tree) olpc_ofw or olpcfw, to denote that this is an OLPC-specific interface. Thus, CONFIG_OLPC_OPEN_FIRMWARE or something along those lines.

- Make it explicit in Kconfig that OLPC_OPEN_FIRMWARE conflicts with X86_PAE, 64BIT, or X86_PAT.

- Change VMALLOC_END in include/asm-x86/pgtable_32.h so the kernel will know to avoid this virtual memory range.

- Add a memory region to arch/x86/mm/dump_tabletables.c.

-hpa
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