Bug 28803 - GDB unable to set $xmm2-9 register but able to set $xmm0-1,10-15 on non-AVX machines
Summary: GDB unable to set $xmm2-9 register but able to set $xmm0-1,10-15 on non-AVX m...
Status: RESOLVED FIXED
Alias: None
Product: gdb
Classification: Unclassified
Component: gdb (show other bugs)
Version: unknown
: P2 normal
Target Milestone: ---
Assignee: Not yet assigned to anyone
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Reported: 2022-01-21 20:24 UTC by Luís Ferreira
Modified: 2022-02-28 18:17 UTC (History)
1 user (show)

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Description Luís Ferreira 2022-01-21 20:24:13 UTC 
When running on my "Intel(R) Xeon(R) CPU E7-4860", I can't set xmm2 to xmm7 registers on GDB. On a more recent CPU "Intel(R) Core(TM) m3-7Y30" this seems to set just fine. I also tested this on a libvirt clean environment with an Intel Core 2 Duo and Intel Ivy Bridge family CPU (emulated settings), and the one without AVX did fail to set.

To reproduce the issue, you can run any process on a non-AVX machine:

$ gdb /usr/bin/bash
.> r -c 'kill -SIGILL $$'
.> p $xmm7.uint128
.> set $xmm7.uint128 = 35322350018591
.> p $xmm7.uint128


If you try with $xmm0 or $xmm1 it works just fine.

Previously reported in https://gcc.gnu.org/bugzilla/show_bug.cgi?id=104169 .
Comment 1 Luís Ferreira 2022-02-28 18:17:59 UTC 
Linux kernel fix is going to land on stable branches soon. I'm closing as resolved.