Re: [Qemu-devel] ARM

[Fabrice Bellard <fabrice.bellard@free.fr>]

Jocelyn Mayer wrote:
 > On Wed, 2003-07-09 at 20:35, Daniel Jacobowitz wrote:
 >
 >> I was just playing with the ARM support, it's great to see it
 >> taking shape :)  Fabrice, are you still investigating it, or does
 >> it work for you?  My local ARM setup crashes a few hundred
 >> instructions into ld.so; a loop runs for too long and hits the top
 >> of the stack.
 >
 >
 > Hello,
 >
 > Maybe a flag problem.. As I was looking the overflow flag
 > calculation, while trying to fix it in my PPC emulation, I noticed
 > that this flag should be masked with (1 << 31) to be correct. Fabrice,
 > could you confirm this point ?

Yes, the overflow flag should be masked with (1 << 31). For ARM, the
masking does not need to be done as the overflow is computed in a
separate variable.

 > It seems to work well in my PPC code...
 >
 > It may also comes from the fact that the qemu Elf loader builds a "buggy"
 > stack. I don't known anything about the ABI for the ARM, but I noticed
 > that the stack wasn't aligned properly on PPC and that some informations
 > were missing, but I don't really know if those infos are vital or
 > not. Even in x86 emulation, the stack is really different from the
 > one built by the Linux kernel (I compared with a linux-2.4.21
 > kernel). I fixed some crashes, changing this code to do the same as
 > the kernel, but dynamic x86 loading is now buggy with that patch...

Yes, alignment is not done properly yet as the elf loader comes from a 
very old Linux kernel. If you except the alignment bug, none of the 
differences should be critical.

Fabrice.