Re: [PATCH] MIPS: Alchemy: Save the Ethernet address before reusing PROM memory

[Matthew Wilcox]

On Fri, Oct 16, 2026 at 10:31:55AM -0700, Florian Fainelli wrote:
> Alchemy keeps pointers into the firmware environment and looks up ethaddr
> when initializing the Ethernet devices. By that point, memory allocation
> can have overwritten the environment, causing prom_getenv() to pass an
> invalid pointer to strchr() and panic during boot.
> 
> On the MTX-1, the struct page layout change in 9ddb3c14afba reduces struct
> page from 40 to 32 bytes and exposes this unreserved firmware memory.
> Bisection and boot tests confirmed that the parent boots while the change
> reproduces the panic.
> 
> Parse the Ethernet address during prom_init(), before registering RAM
> with memblock, and keep the six bytes in kernel-owned init data. Return
> the saved address during device initialization, preserving the existing
> YAMON formats and command-line fallback without reserving a fixed
> low-memory region.
> 
> Fixes: 9ddb3c14afba ("mm: fix struct page layout on 32-bit systems")

This is an inappropriate Fixes line.  That may have exposed the problem
(... 5 years ago; how often is this being tested?) but it's merely
restoring the layout to that which existed two years before that.
The correct Fixes line wuld be something related to this driver.