Messages in this thread | | | Date | Tue, 1 Mar 2011 08:34:37 -0800 | Subject | Re: [RFC PATCH] ARM: Use generic BUG() handler | From | Simon Glass <> |
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On Tue, Mar 1, 2011 at 2:03 AM, Russell King - ARM Linux <linux@arm.linux.org.uk> wrote: > On Tue, Mar 01, 2011 at 10:12:40AM +0100, Mikael Pettersson wrote: >> Russell King - ARM Linux writes: >> > On Tue, Mar 01, 2011 at 08:49:49AM +0000, Russell King - ARM Linux wrote: >> > > On Mon, Feb 28, 2011 at 04:27:43PM -0800, Simon Glass wrote: >> > > > + asm volatile("1:\t.word %c3\n" \ >> > > > + ".pushsection __bug_table,\"a\"\n" \ >> > > > + "2:\t.word 1b, %c0\n" \ >> > > > + "\t.hword %c1, 0\n" \ >> > > > + "\t.org 2b+%c2\n" \ >> > > >> > > %c doesn't work on lots of versions of gcc, which is why we can't use >> > > the generic bug support. There's no way to reliably generate constants >> > > without many compiler versions spitting out a '#' before them. >> > >> > gcc 4.3.2: >> > >> > asm(".word %c0" : : "i" (0)); >> > >> > produces: >> > >> > .word #0 >> > >> > which gas chokes on: >> > >> > /tmp/cc2hGOHd.s:12: Error: bad expression >> > /tmp/cc2hGOHd.s:12: Error: junk at end of line, first unrecognized character is `0' >> > >> > So what this means is that it's impossible to generate constants in >> > assembly with GCC targetting ARM without having them prefixed by '#', >> > which in turn makes it impossible to use the generic BUG support. >> > >> > I reported this bug to gcc folk many years ago. I've no idea which >> > version it has been fixed in or if it's even been fixed. >> >> What's the gcc bugzilla bug number? > > No idea off hand - I'll have to search for that. >
It seems I am lucky with the gcc I am using. I would have thought this would be a pretty fundamental feature, but yes I did notice that %c wasn't used anywhere.
Would this kernel feature be acceptable as a selectable config option on ARM then?
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