Subject: Re: more on non-executable mappings vs. emulations
To: Chuck Silvers <>
From: Christos Zoulas <>
List: tech-kern
Date: 07/12/2004 12:59:18
On Jul 12,  8:12am, (Chuck Silvers) wrote:
-- Subject: Re: more on non-executable mappings vs. emulations

| On Mon, Jul 12, 2004 at 12:32:21PM +0000, Christos Zoulas wrote:
| > I agree that we should not make kernels insecure by default in order to
| > please broken emulations. On the other hand, we should document and
| > explain why emulations break and provide a sysctl to let broken emulated
| > programs run until we supply the tools you mention above. This sysctl
| > should default to "off" and users should be strongly cautioned against
| > turning it "on".
| well, the tools will be much easier to write than the sysctl,
| so I'm only going to do the tools.  I'd prefer that the sysctl thing
| never actually be done, since it opens a big can of worms.
| the ppc ELF tool should be trivial, I'll write it this evening.
| as for the sparc a.out issue, it occurred to me on my morning walk that
| it may be possible to have mprotect() the relevant parts of itself
| before it needs to execute the incorrectly mapped instructions.
| I'll look into this tonight also.

Great. I did not realize that the sysctl would be a lot more difficult
to do than the tools. I am all for doing just the tools then.