Messages in this thread | | | Subject | Re: [PATCH] Use correct x86 reboot vector | From | (Eric W. Biederman) | Date | 11 May 2003 13:16:26 -0600 |
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Matt Mackall <mpm@selenic.com> writes:
> There's a missing piece of behavior here that's probably fatal. > Namely, the next time the CS descriptor is loaded, even with the same > value, the high bits are lost. So, for example, if you're running BIOS > out of ROM, decompressing it into the top of 20-bit address space, > then long jumping to your uncompressed code, you don't want to find > yourself back in ROM. > > Perhaps there's a trick that can be played with loading the descriptor > into CS and then clearing the descriptor table without flushing, but it > sounds rather dubious..
If PE is really disabled that should bit should come for free. And it is why it is so hard to fake this behavior.
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