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Re: Questions about hppa *context functions.
On 01/31/2010 09:15 PM, Carlos O'Donell wrote:
On Sun, Jan 31, 2010 at 11:25 AM, Carlos O'Donell
<carlos@systemhalted.org> wrote:
Helge,
On December 15th, 2009 an additional *context test was added to glibc,
see stdlib/tst-makecontext3.c.
This test fails on hppa with:
~~~
makecontext: does not know how to handle more than 8 arguments
~~~
New patch attached with additional changes:
* Align the incoming stack to 64-bytes.
* Adjust for frame.
* Adjust saved stack pointer.
The following patch allows the new test to pass for the 32-bit runtime.
I can't guarantee this works for a 64-bit runtime.
Helge, can you comment on the attached patch?
Carlos,
thanks a lot for your work!
First of all, if it works, I'm fine with it.
One minor question:
I'm used to test sizeof long instead of sizeof int to check for 32/64bit.
You changed it to "(sizeof(unsigned int) == 8)".
I always thought a long is usually the type of a register, while an int can be anything.
1. Why limit the number of input arguments to 8?
I didn't had real reasons.
At some point I read that software usually should not rely on the fact that the
*context funtions can handle more than 4 arguments. To be on the safe side, software
should better hand over a pointer to a struct in one of the first 4 arguments.
But with your patch, which extends it for parisc to more than 8 arguments, it's even better :-)
2. It doesn't appear that the current implementation transfers
ucp->uc_stack.ss_sp to the stack pointer when makecontext() is called.
You seem to have fixed this in your patch.
3. POSIX says that all the arguments must be of type int, but in a
comment you write "XXX: This implementation only handles integer
arguments."
Is there any reason this comment should stay there?
Yep. Just drop it.
Again, I didn't tested you patch, but just by looking at it, it seems OK.
Thanks,
Helge