Messages in this thread | | | Subject | Re: [ACPI] Re: [PATCH/RFC] exposing ACPI objects in sysfs | From | Alex Williamson <> | Date | Tue, 21 Sep 2004 13:13:55 -0600 |
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On Tue, 2004-09-21 at 21:06 +0200, Andi Kleen wrote: > On Tue, Sep 21, 2004 at 07:26:25PM +0200, Pavel Machek wrote: > > > +struct special_cmd { > > > + u32 magic; > > > + unsigned int cmd; > > > + char *args; > > > +}; > > > > Talk to Andi Kleen; passing such structures using read/write is evil, > > because (unlike ioctl) there's no place to put 32/64bit > > translation. Imagine i386 application running on x86-64 system. > > Yes, Pavel is right. Please don't pass pointers by read/write > because it cannot be 32bit emulated.
All pointers are actually interpreted as offsets into the buffer for this interface. They are not actually pointers. I believe the 32bit emulation problem is limited to an ILP32 application generating data structures appropriate for an LP64 kernel. While difficult, it can be done.
Alex
-- Alex Williamson HP Linux & Open Source Lab
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