Messages in this thread | | | Date | Sat, 1 May 1999 02:59:56 -0700 | From | David Miller <> | Subject | Re: 64bit port |
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From: hpa@transmeta.com (H. Peter Anvin) Date: 1 May 1999 09:39:27 GMT
I think that was only UltraSPARC I.
Not true.
All currently shipping UltraSparc's have at least one of the two 64-bit lockup bugs. On the Ultra-I the user can do it no matter where the text section is mapped, this is why Solaris doesn't offer 64-bit installation by default on the < 250Mhz Ultra-I's which are the chips affected by this first bug.
All UltraSparc chips (to my knowledge) are effected by the second hw bug, which can only be triggered if the user can execute code in the top of low 2GB of the 64-bit address space (it involves doing a PC relative call which over/under-flows the program counter across the 64-bit top/bottom addresses, while doing an access into the VA space hole in the delay slot, or something like this, I don't know the exact trigger sequence yet). This is why Solaris-7 does not allow 64-bit userspace to map anything in these areas in 64-bit mode, which as a side-effect makes the medium-low code model close to useless.
When Jakub and I get the 64-bit userland bootstrapped, I'll start running crashme to learn what the exact instruction sequences are so we have a chance at coding a more suitable workaround than what Solaris has chosen.
Later, David S. Miller davem@redhat.com
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