On Wed, Dec 10, 2008 at 1:29 PM, Myles Watson <[EMAIL PROTECTED]> wrote:
> > > > -----Original Message----- > > From: [EMAIL PROTECTED] [mailto: > [EMAIL PROTECTED] > > On Behalf Of Carl-Daniel Hailfinger > > Sent: Wednesday, December 10, 2008 11:18 AM > > To: Corey Osgood > > Cc: Segher Boessenkool; coreboot > > Subject: Re: [coreboot] [PATCH][v3] Check that CAR and ROM areas > > don'tcollide > > > > Hi Segher, > > > > is the last test below with 0x100000000 (2^32) in the formula guaranteed > > to work or may cpp truncate the results to 32 bit? I'd rather avoid > > introducing a test that can never trigger. > > ...snip... > > > What you actually want is this test: > > #if CONFIG_CARBASE + CONFIG_CARSIZE + (CONFIG_COREBOOT_ROMSIZE_KB * 1024) > > > 0x100000000 > > To avoid that problem, maybe we should /1024 instead of *. > #if CONFIG_CARBASE/1024 + CONFIG_CARSIZE/1024 + CONFIG_COREBOOT_ROMSIZE_KB > > > 1<<22 > > I realize that 1<<22 isn't pretty, but the rest doesn't seem too bad. > > Thanks, > Myles > > I'm probably missing something, but I'm not seeing the off-by-one error in the original function. CONFIG_CARBASE and 0xffffffff are both addresses, you could say they're both off by one, but by comparing them the problem is negated. You could rearrange it to 0xffffffff - (CONFIG_CARBASE + CONFIG_CARSIZE) < CONFIG_COREBOOT_ROMSIZE_KB * 1024 which should, AFAIK, compare the remaining space with the ROM size. Right? Thanks, Corey
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