Hi Adhemerval, On Thu, Oct 19, 2023 at 09:31:39AM -0300, Adhemerval Zanella wrote: > It was added on glibc 2.33 as a way to improve path search, since > legacy hardware capabilities combination scheme do not scale > properly with new hardware support. The legacy support was removed > on glibc 2.37, so it is the only scheme currently supported. > > Signed-off-by: Adhemerval Zanella <adhemerval.zanella@xxxxxxxxxx> > --- > man8/ld.so.8 | 48 +++++++++++++++++++++++++++++++++++++++++++++++- > 1 file changed, 47 insertions(+), 1 deletion(-) > > diff --git a/man8/ld.so.8 b/man8/ld.so.8 > index cf03cb85e..3025da861 100644 > --- a/man8/ld.so.8 > +++ b/man8/ld.so.8 > @@ -208,6 +208,14 @@ The objects in > .I list > are delimited by colons. > .TP > +.BI \-\-glibc-hwcaps-mask " list" > +only search built-in subdirectories if in > +.IR list . > +.TP > +.BI \-\-glibc-hwcaps-prepend " list" > +Search glibc-hwcaps subdirectories in > +.IR list . > +.TP > .B \-\-inhibit\-cache > Do not use > .IR /etc/ld.so.cache . > @@ -808,7 +816,7 @@ as a temporary workaround to a library misconfiguration issue.) > .I lib*.so* > shared objects > .SH NOTES > -.SS Hardware capabilities > +.SS Legacy Hardware capabilities (from glibc 2.5 to glibc 2.37) > Some shared objects are compiled using hardware-specific instructions which do > not exist on every CPU. > Such objects should be installed in directories whose names define the > @@ -843,6 +851,44 @@ z900, z990, z9-109, z10, zarch > .B x86 (32-bit only) > acpi, apic, clflush, cmov, cx8, dts, fxsr, ht, i386, i486, i586, i686, mca, mmx, > mtrr, pat, pbe, pge, pn, pse36, sep, ss, sse, sse2, tm > +.SS glibc Hardware capabilities (from glibc 2.33) > +The legacy hardware capabilities combinations has the drawback where each > +feature name incur in cascading extra paths added on the search path list, Use semantic newlines: The legacy hardware capabilities combinations has the drawback where each feature name incur in cascading extra paths added on the search path list > +adding a lot of overhead on > +.B ld.so > +during library resolution. > +For instance, on x86 32-bit, if the hardware > +supports > +.B i686 > +and > +.B sse2 .BR sse2 , Otherwise, you'll see a space after the comma. BR alternates bold and roman for its arguments, and puts them together without spaces. > +, the resulting search path will be > +.B > +i686/sse2:i686:sse2:. . .BR i686/sse2:i686:sse2:. . > +A new capability > +.B newcap > +will set the search path to > +.B > +newcap/i686/sse2:newcap/i686:newcap/sse2:newcap:i686/sse2:i686:sse2: . .BR newcap/i686/sse2:newcap/i686:newcap/sse2:newcap:i686/sse2:i686:sse2: . > + .PP > +glibc 2.33 added a new hardware capability scheme, where each ABI can define s/, /,\n/ > +a set of paths based on expected hardware support. > +Each path is added depending of the hardware of the machine, and they are not s/, /,\n/ > +combined together. > +They also have priority over the legacy hardware capabilities. The following s/\. /\.\n/ Cheers, Alex > +paths are currently supported. > +.TP > +.B PowerPC (64-bit little-endian only) > +power9, power10 > +.TP > +.B s390 (64-bit only) > +z13, z14, z15, z16 > +.TP > +.B x86 (64-bit only) > +x86-64-v2, x86-64-v3, x86-64-v4 > +.PP > +The glibc 2.37 removed support for the legacy hardware capabilities. > +. > .SH SEE ALSO > .BR ld (1), > .BR ldd (1), > -- > 2.34.1 > -- <https://www.alejandro-colomar.es/>
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