Re: NVidia glx stuff dies in sysarch(I386_SET_LDT, ...)

From: Bruce Evans <bde_at_zeta.org.au>
Date: Sat, 2 Aug 2003 19:38:16 +1000 (EST)
On Fri, 1 Aug 2003, Julian Elischer wrote:

> looking at it further, it appears that NLDT is not really a
> 'reservation' as much as a description of how much space we may
> need to allocate initially.

Correct, except it seems that there are some bugs from the kernel using
the code and data selectors see another reply).

> I think that it wouldn't matter (for example) if you used one of the
> existing defined numbers as long as you are not running a program that
> used them..
> i.e you could use as you are not a BSDI binary that needs it.

Even changing the code and data selectors so that user code can't run
should be just foot shooting.  It seems to be allowed before rev.1.84.
The LDT is a user resource and the kernel can do very little about
applications and libraries mismanaging it.  It can just help them
manage it.  Dynamic allocation seems to be a correct first step towards
letting them manage it.

> Also it's interesting to note that '0' is defined..
> this is intersting as a value of a segment register of '0'
> is not allowed from my memory.
> I guess that only applies to GDTEs.

Correct.

Bruce
Received on Sat Aug 02 2003 - 00:38:29 UTC

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