Re: [PATCH 03/25] xen: Add nosegneg capability to the vsyscall page notes

Roland McGrath wrote: >> I have to admit I still don't really understand all this. Is it >> documented somewhere? >> > > I have explained it in public more than once, but I don't know off hand > anywhere that was helpfully recorded. > Thanks very much. I'd been poking about, but the

Re: [PATCH 03/25] xen: Add nosegneg capability to the vsyscall page notes

Roland McGrath wrote: I have to admit I still don't really understand all this. Is it documented somewhere? I have explained it in public more than once, but I don't know off hand anywhere that was helpfully recorded. Thanks very much. I'd been poking about, but the closest I

Re: [PATCH 03/25] xen: Add nosegneg capability to the vsyscall page notes

> I have to admit I still don't really understand all this. Is it > documented somewhere? I have explained it in public more than once, but I don't know off hand anywhere that was helpfully recorded. > What does "hwcap 0 nosegneg" actually mean? What does the "0" mean here? ldconfig is

Re: [PATCH 03/25] xen: Add nosegneg capability to the vsyscall page notes

Roland McGrath wrote: >> + * It should contain: >> + * hwcap 0 nosegneg >> + * to match the mapping of bit to name that we give here. >> > > This needs to be "hwcap 0 nosegneg" to match: > > >> +NOTE_KERNELCAP_BEGIN(1, 2) >> +NOTE_KERNELCAP(1, "nosegneg") >> +NOTE_KERNELCAP_END >> >

Re: [PATCH 03/25] xen: Add nosegneg capability to the vsyscall page notes

> + * It should contain: > + * hwcap 0 nosegneg > + * to match the mapping of bit to name that we give here. This needs to be "hwcap 0 nosegneg" to match: > +NOTE_KERNELCAP_BEGIN(1, 2) > +NOTE_KERNELCAP(1, "nosegneg") > +NOTE_KERNELCAP_END The actual bits you are using should be fine.

[PATCH 03/25] xen: Add nosegneg capability to the vsyscall page notes

Add the "nosegneg" fake capabilty to the vsyscall page notes. This is used by the runtime linker to select a glibc version which then disables negative-offset accesses to the thread-local segment via %gs. These accesses require emulation in Xen (because segments are truncated to protect the

[PATCH 03/25] xen: Add nosegneg capability to the vsyscall page notes

Add the nosegneg fake capabilty to the vsyscall page notes. This is used by the runtime linker to select a glibc version which then disables negative-offset accesses to the thread-local segment via %gs. These accesses require emulation in Xen (because segments are truncated to protect the

Re: [PATCH 03/25] xen: Add nosegneg capability to the vsyscall page notes

+ * It should contain: + * hwcap 0 nosegneg + * to match the mapping of bit to name that we give here. This needs to be hwcap 0 nosegneg to match: +NOTE_KERNELCAP_BEGIN(1, 2) +NOTE_KERNELCAP(1, nosegneg) +NOTE_KERNELCAP_END The actual bits you are using should be fine. (You're

Re: [PATCH 03/25] xen: Add nosegneg capability to the vsyscall page notes

Roland McGrath wrote: + * It should contain: + * hwcap 0 nosegneg + * to match the mapping of bit to name that we give here. This needs to be hwcap 0 nosegneg to match: +NOTE_KERNELCAP_BEGIN(1, 2) +NOTE_KERNELCAP(1, nosegneg) +NOTE_KERNELCAP_END The actual bits you are

Re: [PATCH 03/25] xen: Add nosegneg capability to the vsyscall page notes

I have to admit I still don't really understand all this. Is it documented somewhere? I have explained it in public more than once, but I don't know off hand anywhere that was helpfully recorded. What does hwcap 0 nosegneg actually mean? What does the 0 mean here? ldconfig is usually run