[Bug tdep/28355] [aarch64] regcache.cc:257: A problem internal to GDBserver has been detected. Unknown register tag_ctl requested

["sourceware at johnea dot net" <sourceware-bugzilla@sourceware.org>]

https://sourceware.org/bugzilla/show_bug.cgi?id=28355

--- Comment #17 from sourceware at johnea dot net ---
OK, one slight twist. The failure occurs on an archlinuxarm rootfs, with
gdbserver 11.1.

When I boot into Xilinx's petalinux rootfs, remote debug works correctly, with
gdbserver 9.2.

In both cases the x86 host runs aarch64-linux-gnu-gdb 11.1.

The data asked for, from both platforms:

>From aarch64 petalinux command line:
# LD_SHOW_AUXV=1 /bin/true
AT_SYSINFO_EHDR:      0xffffaf62c000
AT_??? (0x33): 0x1270
AT_HWCAP:             8fb
AT_PAGESZ:            4096
AT_CLKTCK:            100
AT_PHDR:              0xaaaaddbb0040
AT_PHENT:             56
AT_PHNUM:             9
AT_BASE:              0xffffaf5fb000
AT_FLAGS:             0x0
AT_ENTRY:             0xaaaaddbb1740
AT_UID:               0
AT_EUID:              0
AT_GID:               0
AT_EGID:              0
AT_SECURE:            0
AT_RANDOM:            0xffffd9b84c38
AT_HWCAP2:            0x0
AT_EXECFN:            /bin/true
AT_PLATFORM:          aarch64


>From aaarch64 archlinuxarm command line:
# LD_SHOW_AUXV=1 /bin/true
AT_SYSINFO_EHDR:      0xffffa2f68000
AT_??? (0x33): 0x1270
AT_HWCAP:             8fb
AT_PAGESZ:            4096
AT_CLKTCK:            100
AT_PHDR:              0xaaaae9850040
AT_PHENT:             56
AT_PHNUM:             9
AT_BASE:              0xffffa2f37000
AT_FLAGS:             0x0
AT_ENTRY:             0xaaaae98516c8
AT_UID:               0
AT_EUID:              0
AT_GID:               0
AT_EGID:              0
AT_SECURE:            0
AT_RANDOM:            0xffffc9115218
AT_HWCAP2:            0x0
AT_EXECFN:            /bin/true
AT_PLATFORM:          aarch64

The gdb output was captured by setting:
(gdb) set logging debugredirect on
(gdb) set logging on
(gdb) set debug remote 1
(gdb) set debug remote-packet-max-chars -1
(gdb) target remote zcu102:1234

When using the archlinuxarm rootfs, gdbserver 11.1, the (gdb) target remote
command led to immediate crash of gdbserver on the target. Data attached as:
gdbserver-11.1-archlinuxarm-failed.txt.gz

When using the petalinux rootfs, gdbserver 9.2, files and libraries were read
as expected, and I continued to set breakpoints, single step, and the hello
application ran and terminated successfully. Data attached as:
gdbserver-9.2-petalinux-pass.txt.gz

Don't be fooled by the filenames, both of these captures occurred on the same
x86 host, running aarch64-linux-gnu-gdb 11.1. The names represent the rootfs
and gdbserver version on the remote target.

Don't know if it's related, but I was also unable to get tcf-agent working on
the archlinuxarm rootfs, whereas it works on the petalinux rootfs.

I'd actually prefer to run the archlinux aarch64 rootfs, and I hope this data
capture can help illuminate the bug, and lead to a fix.

Please let me know if I can capture more data, or test updates...

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