Re: PATCH: usb: descriptor structures have to be packed
Oliver Neukum <[email protected]>
| Newsgroups | gmane.linux.usb.devel |
|---|---|
| Message-ID | <[email protected]> |
Am Mittwoch, 7. Februar 2007 19:23 schrieb David Brownell: > On Wednesday 07 February 2007 4:25 am, Oliver Neukum wrote: > > > 1. Disallow any padding > > 2. Assume the structure may be in unaligned memory > > > > Issue number #1 is usually handled by the USB specification. > > Key word "usually"; they haven't AFAIK promised to do so. True. For descriptors it doesn't really matter much. > > #2 is not. Therefore packed data structures will make inferior code > > even in the case we alloc the data structure ourselves. [..] > Are you honestly suggesting the performance impact of this could posssibly > outweigh the maintainence nightmare of needing to explicitly code unaligned > access into all the kernel and userspace code that touches descriptor fields? As long as you leave alone the control requests I am all in favor of packed. Regards Oliver ------------------------------------------------------------------------- Using Tomcat but need to do more? Need to support web services, security? Get stuff done quickly with pre-integrated technology to make your job easier. Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642 _______________________________________________ [email protected] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel