memcpy_cpu on 64bit arm

[Christian Helmuth]

Hello,

On Mon, Jan 23, 2023 at 15:56:48 CET, Michael Grunditz wrote:
> On Mon, 23 Jan 2023 at 14:15, Michael Grunditz <michael.grunditz at gmail.com> wrote:
> > Anyway init crashes somewhere.
> >
> > 2043 MiB RAM and 64533 caps assigned to init
> > no RM attachment (READ pf_addr=0x81 pf_ip=0x9f3f4 from pager_object:
> > pd='init' thread='init')
> > Warning: page fault, pager_object: pd='init' thread='init' ip=0x9f3f4
> > fault-addr=0x81 type=no-page
> 
> I *think* it fails right in start of first child. It seems ok around
> the starting.
> The last memcpy seems ok. I have printed both buffers and they are identical.

I'm wondering why you replaced the general memcpy() in the first place
as this brings maximal (potential negative) impact in many places. You
could alternatively just optimize your framebuffer blitting and
proceed with your porting work.

Also, it is not known which NEON instructions and registers your
memcpy utilizes. I'm not an ARM expert but: Does the current
FPU-switching implementation of base-hw suffice or do you need to
save/restore extended state? As you do not share your developments
(i.e. source code) with the public it is hard to provide specific
help.

Any information which code is at 0x9f3f4 in ld.lib.so?

Greets
-- 
Christian Helmuth
Genode Labs

https://www.genode-labs.com/ · https://genode.org/
https://twitter.com/GenodeLabs · https://genodians.org/

Genode Labs GmbH · Amtsgericht Dresden · HRB 28424 · Sitz Dresden
Geschäftsführer: Dr.-Ing. Norman Feske, Christian Helmuth