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On Fri, 18 Nov 2005, David S. Miller wrote: > > The recent vbetool suspend-from-ram datapoint shows that it might be > important that the BIOS data area is application local, > ie. MAP_PRIVATE. Ie. it works only if the writes are not performed > to the real BIOS data page. Interesting. I haven't dared reach that conclusion yet. > If true, that means the MAP_PRIVATE+VM_UNPAGED case has legit users. > Although, such applications could just copy the interrupt vector plus > BIOS data area into an anonymously mapped region and have the vm86 > execution work off that instead of the /dev/mem mapping. Yes, they could indeed. Would save the kernel contortions. > So, just to make sure this all adds up, a PROT_WRITE+MAP_PRIVATE > mapping of /dev/mem results in any pages written to being COW'd. > Right? Yes, in everything before 2.6.15-rc1, and again with my patches. > It is a good question as to which cases doing stuff like this want to > make modifications to the real BIOS data area, and which ones do not. > Aparently vbetool does not. Hugh - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ | ||||||||||||
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