On Thu, Jan 12, 2006 at 05:22:47PM +0000, David Vrabel wrote: > Russell King wrote: > > BTW, it's worth noting that the new EABI stuff has it's own set of > > problems. We have r0 to r6 to pass 32-bit or 64-bit arguments. > > With EABI, 64-bit arguments will be aligned to an _even_ numbered > > register. > > Is there a reason for this alignment requirement?
I think it comes from the 64-bit accessing instructions (ldrd/strd) having the restriction that they only take an even numbered 32-bit register. The immediately consecutive higher numbered 32-bit egister is used as the other half of the number. Think about it as the x86 32-bit eax register being made up of 16-bit ah and al registers. Only we call then r0, r1 etc not eax, ah and al (and they're twice the size.) -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: 2.6 Serial core ------------------------------------------------------- This SF.net email is sponsored by: Splunk Inc. Do you grep through log files for problems? Stop! Download the new AJAX search engine that makes searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
