Re: [PATCH] include: sbi_platform: Increase default stack size

On 25/5/26 11:23 pm, Anirudh Srinivasan wrote:
> Hi Vivian,
> 
> On Sun, May 24, 2026 at 12:53 AM Vivian Wang <[email protected]> wrote:
>>
>> sbi_misaligned_v_ld_emulator() has a local buffer (namely mask) which is
>> 8192 bytes in size, so the default stack size is not enough. Double it
>> to 16384.
>>
>> This stack overflow can be observed by any S-mode software and leads to
>> M-mode crash or unexpected behavior, as long as the S-mode software does
>> not enable FWFT misaligned delegation [1]. This may be considered a
>> temporary fix until further fixes are made to misaligned handling [2].
>>
>> Link: https://lore.kernel.org/linux-riscv/nrvt74qnojaubiwjo37ums4lnclu466hovwrhmtbag6f5uhrql@q6msoe2oto4b # [1]
>> Link: https://lore.kernel.org/opensbi/[email protected] # [2]
>> Signed-off-by: Vivian Wang <[email protected]>
> 
> There was a similar patch [1] from few days ago that makes this a
> Kconfig option. Either option would work to fix the bug I encountered.
Making the stack size configurable is nice, but it's not really a fix 
for this bug if the user has to know to increase the size.

So some combination of the two patches would be best IMHO.

What I'm not clear on is whether just bumping to a 16KB minimum always 
is acceptable. Are there folks running on memory constrained systems 
that don't want stack that big?

If you're not building the vector emulation code in then 8KB is 
presumably fine.

cheers

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