[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH] cleanup for __start_xen()
Keir Fraser wrote: > On 30/11/2009 17:42, "Ian Jackson" <Ian.Jackson@xxxxxxxxxxxxx> wrote: > >> I wrote: >>> Xiao Guangrong writes ("[Xen-devel] [PATCH] cleanup for __start_xen()"): >>>> - if ( !initial_images_start && (s < e) && >>>> + if ( !initial_images_start && >>> This is wrong. s and e are uint64_t so if !(s < e), (e-s) will be >>> large and positive. >> I see this has already been applied (20523). It should be reverted, I >> think. > > None of the if() blocks in the loop will make e<s, as that would imply that > the block had allocated itself a chunk of memory that starts below s. So it > is actually safe to remove the checks, as we know e>=s. But now I look at it > I think I broke the module-relocation block some time ago -- it ends up with > 'e' being too large by modules_headroom. :-( Will look into that more > tomorrow... > I thinks remove this judgment is very safe, because we have judge it at the begin of this loop: for ( i = boot_e820.nr_map-1; i >= 0; i-- ) { uint64_t s, e, mask = (1UL << L2_PAGETABLE_SHIFT) - 1; <snip> if ( (boot_e820.map[i].type != E820_RAM) || (s >= e) ) /* NOTICE HERE*/ continue; /* it must s < e while run below code, not need check it again ... */ ...... } Thanks, Xiao _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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