Re: [uml-devel] [UML combo patch] uml-combo-2.6.0-A7

[BlaisorBlade <blaisorblade_spam@yahoo.it>]

Alle 11:11, lunedì 5 gennaio 2004, Ingo Molnar ha scritto:
> * BlaisorBlade <blaisorblade_spam@yahoo.it> wrote:
> > Two questions:
> > 1) I've added the G-03(this fixes the empty /proc/kallsyms issue), H-03
> > and H-04(for Makefiles cleanups) patches. Would you try them?
>
> i'll try these too. Your bugfixes/collections are now perfectly fine for
> 2.6.0 UML experimentation so i'll use them instead of spinning my own
> ones. (your ones are also better split up.)

Thanks, my first purpose has in fact been to make it ready for inclusion in 
mainline, and I've finally replaced the A-03 and A-04 patches, which couldn't 
be accepted probably.

> > 2)Have you given a look to the mm/memory.c change (what I'd split into
> > A-04)?  Do you think that change can be safe even for the host kernel?
>
> tricky stuff - hand-building vmas is fragile like hell, and the vsyscall
> stuff is far from simple too. What is the main purpose of your change?

It wasn't a change that *I* did. I just found that change inside the patch 
from Jeff Dike, and I separated it because I thought it was a bit risky for 
the host, but I wasn't able to replace it. In fact I've always been warning 
"apply that for UML and remove it for the host", even when I didn't 
understand it.

In fact now I've posted the B-02 patch which replaces it; for a complete 
description of the replacement, see the message (in this ML)"Replacement of 
A-04 patch for mm/memory.c for UML/2.6".

However, I just think that while mainstream kernel changed that piece of code 
from using FIXADDR_ to using FIXADDR_USER_, Jeff simply forgot to do this; 
the patch was meant just to fix compilation (FIXADDR_USER_START is not a 
compile-time constant for UML, so you can't compile mm/memory.c without a 
patch).

In fact, in older UML patches, the kernel code *did* use FIXADDR_START and the 
patch didn't change what the code did.

Also, for what I understand (I do want to be corrected if I'm wrong), the 
interested piece of code allows a user-space process to execute the vsyscall 
stub code, but it must not allow anything else to go in the process address 
space.

Bye and thanks for the interest!
-- 
cat <<EOSIGN
Paolo Giarrusso, aka Blaisorblade
Linux Kernel 2.4.23/2.6.0 on an i686; Linux registered user n. 292729
EOSIGN



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