ESP8266 Community Forum

- Sat Sep 06, 2014 7:14 pm #272 It is in the config overlay they made for their specific processor.
xtensa-config-overlay.tar.gz

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xtensa-config-overlay.tar.gz

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Where I get my modules

- Sat Sep 06, 2014 7:15 pm #273 config/core.h:# define XCHAL_HAVE_PTP_MMU 1 /* have full MMU (with page table [autorefill] and protection) */

Where I get my modules

- Sat Sep 06, 2014 7:53 pm #277 Please re-open and read that exact file. The line is not there. Regarding XCHAL_HAVE_PTP_MMU, there's only one line (line 446) clearly defining it 0.

You seem to refer to the core.h in the XtDevTools, which does include the following:

Code: Select all#if 0
#if XCHAL_HAVE_TLBS && !XCHAL_HAVE_SPANNING_WAY && XCHAL_ITLB_ARF_WAYS > 0 && XCHAL_DTLB_ARF_WAYS > 0 && XCHAL_MMU_RINGS >= 2
# define XCHAL_HAVE_PTP_MMU      1   /* have full MMU (with page table [autorefill] and protection) */
#else
# define XCHAL_HAVE_PTP_MMU      0   /* don't have full MMU */
#endif
#endif

Take careful note of the first line here: it effectively comments out the rest of the block, rendering XCHAL_HAVE_PTP_MMU undefined.

Once again, there is absolutely no evidence that this core has an MMU that does anything else than plain region protection. The overlay file and the core configuration summary support the assumption that there is no sophisticated MMU, while the existence of region protection is once again supported by the EXCCAUSE.

- Sat Sep 06, 2014 8:04 pm #279 After poking around in those files I agree that it does not look like the MMU is present. But it would have been fun to play with virtual memory in a chip this small.

So has anyone determined how much RAM/ROM is really in the chip?

Where I get my modules