[OpenBIOS] [PATCH] sparc64: fix registers dealing with client

[Blue Swirl]

On 7/11/09, Igor Kovalenko <igor.v.kovalenko at gmail.com> wrote:
> On Fri, Jul 10, 2009 at 11:20 PM, Blue Swirl<blauwirbel at gmail.com> wrote:
>
> > On 7/6/09, Igor Kovalenko <igor.v.kovalenko at gmail.com> wrote:
>  >> Hi!
>  >>
>  >>  This patch improves previous proposal and adds:
>  >>
>  >>  - save/restore global registers across client interface calls.
>  >>  Since OS kernel generally has it's own idea of what
>  >>  the ABI is we have to follow this requirement.
>  >>
>  >>  - adjust stack to allow using unoptimized openbios
>  >>  build with linux kernel. Linux provides only 128 bytes
>  >>  on stack which is not enough to save arguments by
>  >>  code generated with gcc -O0
>  >>
>  >>  - fix switch_to so it actually could be used to switch
>  >>  to client image. context pointer must be volatile to
>  >>  prevent gcc optimizing out stores to it.
>  >>
>  >>  Signed-off-by: igor.v.kovalenko at gmail.com
>  >
>  > Thanks, but with the patch applied, SILO in most of my test images no
>  > longer boots. For example, HelenOS 0.2.0.5:
>  > OpenBIOS for Sparc64
>  > Configuration device id QEMU version 1 machine id 0
>  > CPUs: 1 x SUNW,UltraSPARC-II
>  > UUID: 00000000-0000-0000-0000-000000000000
>  > Welcome to OpenBIOS v1.0 built on Jul 10 2009 19:12
>  >  Type 'help' for detailed information
>  >
>  > [sparc64] Booting file 'cdrom' with parameters ''
>  > Not a bootable ELF image
>  > Not a Linux kernel image
>  > Loading a.out image...
>  > Loaded 7680 bytes
>  > entry point is 0x4000
>  > Jumping to entry point...
>  > switching to new context: entry point 0x4000 stack 0x00000000ffe51999
>  > SIUnhandled Exception 0x0000000000000068
>  > PC = 0x00000000ffd0ff14 NPC = 0x00000000ffd0ff18
>  > Stopping execution
>  >
>
>
> I found two issues:
>
>  - block reading routines are using significant amount of stack data so
>  4k is not enough (8k seems OK)
>  - must flush windows on caller's stack before switching stack pointer,
>  this causes hard-to-find memory corruption
>
>  Here is updated version, now silo seems to be working here.

Works for me too. Thanks, I'll apply this.