Re: [PATCH v2] MIPS: Alchemy: Save the Ethernet address before reusing PROM memory

[Thomas Bogendoerfer <tsbogend@alpha.franken.de>]

On Fri, Oct 16, 2026 at 03:18:26PM -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: b93ddc4f9156 ("mips: Reserve memory for the kernel image resources")
> Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
> ---
> Changes in v2:
> 
> - corrected Fixes tag to a more appropriate one
> 
>  arch/mips/alchemy/common/prom.c | 23 ++++++++++++++++++++---
>  1 file changed, 20 insertions(+), 3 deletions(-)

applied to mips-fixes

Thomas.

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