[U-Boot] OMAP3 performance regression in 2011.12

Joe Woodward jw at terrafix.co.uk
Mon Jan 9 11:27:25 CET 2012


Commit "armv7: disable L2 cache in cleanup_before_linux()" on 6th Dec 2011 by Aneesh V adds the following:

arch/arm/cpu/armv7/cpu.c:cleanup_before_linux()

...
v7_out_cache_disable();
...

The commit message implies this change was to make booting reliable on OMAP4 by disabling L2 cache before jumping to Linux.

However, when running with a stock 3.2 Linux kernel on an OMAP3 it has the effect of massively reducing system performance (when running using an OMAP3-
only 3.2 Linux Kernel on a GUSMTIX Overo OMAP3530).

Therefore, I assume this means that the kernel isn't turning the L2 cache back on for an OMAP3 (at least with my kernel build)!

So, my question is...

Are there any Kconfig options in Linux that will re-enable the L2 cache (something obvious that I've missed), or is this commit just bad-news for OMAP3?

Cheers,
Joe





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