Re: [PATCH] powerpc/8xx: Load modules closer to kernel text

From: Christophe Leroy
Date: Thu Apr 01 2021 - 17:20:19 EST




Le 01/04/2021 à 06:33, Michael Ellerman a écrit :
Christophe Leroy <christophe.leroy@xxxxxxxxxx> writes:
Le 31/03/2021 à 15:39, Michael Ellerman a écrit :
Christophe Leroy <christophe.leroy@xxxxxxxxxx> writes:
On the 8xx, TASK_SIZE is 0x80000000. The space between TASK_SIZE and
PAGE_OFFSET is not used.

Use it to load modules in order to minimise the distance between
kernel text and modules and avoid trampolines in modules to access
kernel functions or other module functions.

Define a 16Mbytes area for modules, that's more than enough.

16MB seems kind of small.

At least on 64-bit we could potentially have hundreds of MBs of modules.


Well, with a 16 MB kernel and 16 MB modules, my board is full :)

Heh.

ARM set it to 16M or 8M.


Even on the more recent board that has 128 MB, I don't expect more than a few MBs of modules in
addition to the kernel which is approx 8M.

But ok, I'll do something more generic, though it will conflict with Jordan's series.

Don't feel you have to. You're the expert on 8xx, not me.


Doing it generic allows to also get it on book3s/32 for free.

Christophe