Intel T8300 Specifications - Page 36

Errata AZ38. Instruction Fetch May Cause a Livelock during Snoops of the L1 Data Cache Problem: A livelock may be observed in rare conditions when instruction fetch causes multiple level one data cache snoops. Due to this erratum, a livelock may occur. Intel has not observed this erratum with any commercially available software. Workaround: It is possible for BIOS to contain a workaround for this erratum. Status: For the steppings affected, see the Summary Tables of Changes. AZ39. Use of Memory Aliasing with Inconsistent Memory Type May Cause a System Hang or a Machine Check Exception Problem: Software that implements memory aliasing by having more than one linear addresses mapped to the same physical page with different cache types may cause the system to hang or to report a machine check exception (MCE). This would occur if one of the addresses is non-cacheable and used in a code segment and the other is a cacheable address. If the cacheable address finds its way into the instruction cache, and the noncacheable address is fetched in the IFU, the processor may invalidate the non-cacheable address from the fetch unit. Any micro-architectural event that causes instruction restart will be expecting this instruction to still be in the fetch unit and lack of it will cause a system hang or an MCE. Implication: This erratum has not been observed with commercially available software. Workaround: Although it is possible to have a single physical page mapped by two different linear addresses with different memory types, Intel has strongly discouraged this practice as it may lead to undefined results. Software that needs to implement memory aliasing should manage the memory type consistency. Status: For the steppings affected, see the Summary Tables of Changes. 36 Specification Update