Messages in this thread | | | Date | Mon, 16 Nov 2009 16:57:16 +0000 | From | Russell King - ARM Linux <> | Subject | Re: [PATCH 2/3] msm: add minimal board file for HTC Dream device |
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On Mon, Nov 16, 2009 at 08:43:20AM -0800, Brian Swetland wrote: > What's the best way to handle a situation where there is no valid > debug uart? Could the arch/platform require DEBUG_LL be unset via > Kconfig directives if it is configured in a way where there is no > valid debug uart?
You're the first to have that issue. Everyone else has a UART they can always direct stuff at.
However, I believe you're making the issue far larger than it really is.
1. If you define the DEBUG_LL macros to be empty, printascii() etc will not touch any mapping.
2. If no mapping is going to be touched by printascii(), does it matter whether a UART is mapped via this early mapping stuff?
The answer to (2) is no.
So, you can still arrange for these fields to be populated with a valid value even if you don't intend to use the resulting mapping. And so there's no need to force DEBUG_LL to be unset.
If you really have no values you can use, make sure you set io_pg_offst to 0x3ffc - the last offset in the L1 page table. This will cause the code to write a single dummy entry at the very top of the page table, which will then be overwritten by the generic ARM arch code for its own use.
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