On 30.07.2019 11:35, Andrew Cooper wrote: > On 30/07/2019 09:42, Jan Beulich wrote: >> On 29.07.2019 19:38, Andrew Cooper wrote: >>> --- a/xen/arch/x86/xen.lds.S >>> +++ b/xen/arch/x86/xen.lds.S >>> @@ -293,14 +293,17 @@ SECTIONS >>> __bss_start = .; >>> *(.bss.stack_aligned) >>> *(.bss.page_aligned*) >>> - *(.bss) >>> - . = ALIGN(SMP_CACHE_BYTES); >>> + . = ALIGN(PAGE_SIZE); >>> __per_cpu_start = .; >>> + *(.bss.percpu.page_aligned) >>> + . = ALIGN(PAGE_SIZE); >> But this goes too far: What we want is for the TSS to occupy a full >> page, not for whatever random other page-aligned object ends up >> last here (should any every appear). > > Come again? This is ridiculous. > > Objects in a section following foo.page_aligned should never end up in > the tail of the final page of foo.page_aligned, because then they are in > the wrong section.
How do you derive "wrong section"? Sections have an alignment and a size. The latter doesn't need to be a multiple of the former. The section ends wherever its size says it ends. Using this property is actually desirable in other cases, to limit waste of space. > A short TSS is a pain to deal with, but even you said you didn't like > the xen_tss idea when you suggested it. > > The name of the section is very deliberately not TSS specific, because > there is plenty of other cleanup which will end up with objects in this > section. Well, if they're all strictly a multiple of PAGE_SIZE, then writing down a respective requirement might be acceptable. But even then I wouldn't be overly happy going that route. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
