[PATCH] ARM: makefile: work around toolchain bug in recent versions of binutils

Will Deacon [off-list ref] writes:

On Thu, Aug 02, 2012 at 07:18:10PM +0100, Russell King - ARM Linux wrote:

quoted

On Thu, Aug 02, 2012 at 04:51:41PM +0100, Will Deacon wrote:

quoted

On Thu, Aug 02, 2012 at 04:30:30PM +0100, Russell King - ARM Linux wrote:

quoted

It might just be easier to specify something like -march=armv4 or
something like that, and then use .arch armv6 where required.

We could do that, but I worry that it will become very messy if/when people
start adding things like virtualisation instructions (hvc and co) to the
entry code. Using the same march flag for kernel and decompressor also keeps
everything consistent.

But you're missing a fundamental point: the decompressor is not designed
to be built like that, it is designed to be built in such a way that it
works unmodified on any CPU type we have to date, whether you're building
a kernel for ARMv4 or ARMv7.

So, the code sequences which are architecture specific are only executed
after we've checked the ID registers to determine what we should be doing
for a particular CPU.

That's fine, *if* we can persuade the tools to build the thing for us. With
march=all, we got what we wanted but now that doesn't seem to work anymore.

and we already had to fix -march=all in the past :
http://sourceware.org/bugzilla/show_bug.cgi?id=12698

So maybe would be easier to try to fix it instead of trying to
workaround it ?

Arnaud