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<a href="https://gitlab.rtems.org/thejpster">Jonathan Pallant</a>
<a href="https://gitlab.rtems.org/rtems/docs/rtems-docs/-/issues/37#note_113173">commented</a>:
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<p dir="auto" style="color: #28272d; margin: 0 0 16px;" align="initial">This bug is caused by new checks in the Rust pointer offset code which detect that the AMBA plug-and-play scan is trying to copy from the very last byte in memory. Some sources say this is UB which is why we now check for it.</p>
<p dir="auto" style="color: #28272d; margin: 0 0 16px;" align="initial">Is it possible to change the AMBA code to <em style="margin-top: 0;">not</em> read from 0xFFFF_FFFF?</p>
<p dir="auto" style="color: #28272d; margin: 0 0 16px;" align="initial">The stack trace is:</p>
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<pre data-canonical-lang="text" class="code highlight js-syntax-highlight language-plaintext" v-pre="true" style='display: block; font-size: 14px; color: #28272d; line-height: 1.6em; overflow-x: auto; border-radius: .25rem; position: relative; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; word-break: break-all; word-wrap: break-word; background-color: #fbfafd; margin: 0 0 16px; padding: 12px; border: 1px solid #dcdcde;'><code style='font-size: inherit; color: inherit; word-wrap: normal; word-break: keep-all; background-color: inherit; border-radius: .25rem; white-space: pre; margin-top: 0; font-family: "GitLab Mono","JetBrains Mono","Menlo","DejaVu Sans Mono","Liberation Mono","Consolas","Ubuntu Mono","Courier New","andale mono","lucida console",monospace; vertical-align: bottom; overflow-wrap: normal; padding: unset;'><span id="LC1" class="line" lang="plaintext" style="margin-top: 0;">#0 _SPARC_Bad_trap () at ../../../cpukit/score/cpu/sparc/sparc-bad-trap.S:55</span>
<span id="LC2" class="line" lang="plaintext">#1 0x4000a090 in core::ptr::mut_ptr::{impl#0}::add::runtime_add_nowrap (this=0x0, count=1, size=4)</span>
<span id="LC3" class="line" lang="plaintext"> at /home/jonathan/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mut_ptr.rs:1010</span>
<span id="LC4" class="line" lang="plaintext">#2 0x4000a044 in core::ptr::mut_ptr::{impl#0}::add::precondition_check (this=0x0, count=1, size=0)</span>
<span id="LC5" class="line" lang="plaintext"> at /home/jonathan/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ptr/mut_ptr.rs:1021</span>
<span id="LC6" class="line" lang="plaintext">#3 0x40008de8 in core::ptr::mut_ptr::{impl#0}::add<usize> (self=0xfffffffc, count=1)</span>
<span id="LC7" class="line" lang="plaintext"> at /home/jonathan/.rustup/toolchains/nightly-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core/src/ub_checks.rs:77</span>
<span id="LC8" class="line" lang="plaintext">#4 compiler_builtins::mem::impls::copy_forward::copy_forward_aligned_words (dest=0x40025398 <_ISR_Stack_area_begin+3672>, src=0xffffffe0, n=32)</span>
<span id="LC9" class="line" lang="plaintext"> at src/mem/impls.rs:48</span>
<span id="LC10" class="line" lang="plaintext">#5 compiler_builtins::mem::impls::copy_forward (dest=0x40025398 <_ISR_Stack_area_begin+3672>, src=0xffffffe0, n=32) at src/mem/impls.rs:112</span>
<span id="LC11" class="line" lang="plaintext">#6 compiler_builtins::mem::memcpy (dest=0x40025398 <_ISR_Stack_area_begin+3672>, src=0xffffffe0, n=32) at src/mem/mod.rs:25</span>
<span id="LC12" class="line" lang="plaintext">#7 0x40009ab8 in compiler_builtins::mem::memcpy::memcpy (dest=0x40025398 <_ISR_Stack_area_begin+3672>, src=0xffffffe0, n=32) at src/macros.rs:480</span>
<span id="LC13" class="line" lang="plaintext">#8 0x4000d540 in ambapp_scan2 (abus=0x0, ioarea=0, ctx=0x40025418 <_ISR_Stack_area_begin+3800>, parent=0x0, root=0x0)</span>
<span id="LC14" class="line" lang="plaintext"> at ../../../bsps/shared/grlib/amba/ambapp.c:225</span>
<span id="LC15" class="line" lang="plaintext">#9 0x4000c94c in ambapp_plb () at ../../../bsps/sparc/leon3/start/amba.c:76</span>
<span id="LC16" class="line" lang="plaintext">#10 ambapp_plb () at ../../../bsps/sparc/leon3/start/amba.c:59</span>
<span id="LC17" class="line" lang="plaintext">#11 amba_initialize () at ../../../bsps/sparc/leon3/start/amba.c:145</span>
<span id="LC18" class="line" lang="plaintext">#12 0x4001407c in rtems_initialize_executive () at ../../../cpukit/sapi/src/exinit.c:155</span>
<span id="LC19" class="line" lang="plaintext">#13 0x4000c304 in boot_card (cmdline=0x0) at ../../../bsps/shared/start/bootcard.c:74</span>
<span id="LC20" class="line" lang="plaintext">#14 0x400010d0 in hard_reset () at ../../../bsps/sparc/shared/start/start.S:524</span></code></pre>
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