Messages in this thread | | | Date | Fri, 2 Sep 2011 19:56:33 -0700 | Subject | Re: RFD: x32 ABI system call numbers | From | "H.J. Lu" <> |
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On Wed, Aug 31, 2011 at 10:05 AM, H.J. Lu <hjl.tools@gmail.com> wrote: > On Wed, Aug 31, 2011 at 9:46 AM, Linus Torvalds > <torvalds@linux-foundation.org> wrote: >> >> I really think that "x32" should try to aim *VERY* hard at using the >> 64-bit system calls, and seeing itself as being a "32-bit application >> in a 64-bit world". That's not just true for time_t (which I think >> should be 64-bit on anything new that expects to survive for any >> amount of time), but in general. >> > > I have been making x32 to use 64bit system calls as much as possible. > Hopefully, I will get it to work in a week or 2. >
I have an x32 kernel which usea 64bit time_t/timespec/timeval and file system interface:
1. Use 64bit system calls as much as we can. 2. There are 32 compat system calls for x32 to support structure parameters with pointers and longs. 3. Use x86-64 vDSO relocatable files directly to generate x32 vDSO.
We need to make decision on some system calls which take a pointer to structure with long. For example, msg calls take a pointer to
struct msgbuf { long mtype; /* message type, must be > 0 */ char mtext[1]; /* message data */ };
We have 3 choices:
1. Use long long for x32 and use 64bit msg system calls. 2. Keep long for x32 and use compat system call. 3. Add a 4byte padding for x32 and sign-extend from mtype to 4byte padding before passing to 64bit msg system call.
I implemented option 1. I can also implement option 2 or 3.
Thanks.
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