>On 2002-04-25 17:57:38, J. Weeks wrote:
>>On 2002-04-25 06:55:42, blito wrote:
>>hi
>>if i define an LDG selector in the GDT. Example : 0x8
>>with CPL=3, any program can access it???.
>
>You define LDT descriptors in the GDT, and provide
>RPL's not CPL's. You can set the LDT's descriptor
>to RPL=0, if you want. The OS is the only one
>that can execute the LDTR instruction anyway,
>so it's rather pointless to have an RPL of anything
>more than 0 for an LDT descriptor.
>
>>i don´t understand where lies the protection.
>
>Just set RPL=0 so only the OS can access. Your
>applications can still use the LDT, because inside
>the LDT you provide other descriptors to memory
>address. THOSE descriptors can have
>an RPL of 3, if you want.
>
>>please could anybody help me!!!.
>>i'm in troubles.
>
>Hmm... I'm pretty sure that's accurate, but now
>I'm starting to doubt myself (I never used
>LDT's, myself). Can anybody confirm any of the
>above?
>
>Thanks,
>Jeff