Re: [PATCH] ARM: allow DEBUG_UNCOMPRESS for omap2plus

[Stephen Warren <swarren@wwwdotorg.org>]

On 07/31/2013 12:46 AM, Tony Lindgren wrote:
> * Stephen Warren <swarren@wwwdotorg.org> [130730 16:08]:
>> On 07/30/2013 04:52 PM, Russell King - ARM Linux wrote:
>>> On Tue, Jul 30, 2013 at 04:49:18PM -0600, Stephen Warren wrote:
>>>> From: Stephen Warren <swarren@nvidia.com>
>>>>
>>>> DEBUG_UNCOMPRESS was previously disallowed for omap2plus due to
>>>> omap2plus.S's use of .data, which is not allowed in the decompressor.
>>>> Solve this by placing that data into .text when building the file into
>>>> the decompressor. This relies on .text actually being writable in the
>>>> decompressor, which it is in practice.
>>>
>>> Unless you decide to use ZBOOT and flash the zImage.
>>
>> I knew there had to be a catch:-)
>>
>> I have no idea if ZBOOT is a use-case that's relevant to OMAP?
>>
>> On Tegra at least (the same issue applies to the other patch I just
>> sent), that use-case is almost impossible; even if the boot ROM directly
>> booted a kernel, the boot ROM is hard-coded to copy whatever it's
>> booting to SDRAM first, although I suppose if that was a boot-loader it
>> could just jump back to a ROM location. That said, NOR flash is
>> extremely rare on Tegra. So, I don't know if we care about this issue.
>>
>> Is it reasonable to just say "If you use ZBOOT, don't enable
>> DEBUG_UNCOMPRESS"? Perhaps these patches should not completely remove
>> the !DEBUG_TEGRA_UART from config DEBUG_UNCOMPRESS, but instead say:
>>
>> default y if DEBUG_LL && (!DEBUG_TEGRA_UART || !ZBOOT)?
> 
> I think we're best off removing the remaining uncompress code
> configured port detection features as the port properties are now
> defined in kconfig anyways. That simplifies the code quite a bit.

If you want to do that with OMAP, I'm happy to drop this patch.

For Tegra, automatic determination of the DEBUG_LL UART is rather
useful, so I'm not going to give that up:-)