RE: [PATCH V2,net-next, 3/3] net: mana: Add support for jumbo frame

[Haiyang Zhang]

> -----Original Message-----
> From: Jacob Keller <jacob.e.keller@xxxxxxxxx>
> Sent: Tuesday, April 11, 2023 7:13 PM
> To: Haiyang Zhang <haiyangz@xxxxxxxxxxxxx>; linux-hyperv@xxxxxxxxxxxxxxx;
> netdev@xxxxxxxxxxxxxxx
> Cc: Dexuan Cui <decui@xxxxxxxxxxxxx>; KY Srinivasan <kys@xxxxxxxxxxxxx>;
> Paul Rosswurm <paulros@xxxxxxxxxxxxx>; olaf@xxxxxxxxx;
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> ast@xxxxxxxxxx; Ajay Sharma <sharmaajay@xxxxxxxxxxxxx>;
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> Subject: Re: [PATCH V2,net-next, 3/3] net: mana: Add support for jumbo
> frame
> 
> 
> 
> On 4/7/2023 1:59 PM, Haiyang Zhang wrote:
> > During probe, get the hardware-allowed max MTU by querying the device
> > configuration. Users can select MTU up to the device limit.
> > When XDP is in use, limit MTU settings so the buffer size is within
> > one page.
> > Also, to prevent changing MTU fails, and leaves the NIC in a bad state,
> > pre-allocate all buffers before starting the change. So in low memory
> > condition, it will return error, without affecting the NIC.
> >
> 
> What happens if XDP gets enabled after MTU larger than PAGE_SIZE is set?
> Will XDP fail to enable in that case?

Yes, XDP program will fail to enable if MTU is too large.

Thanks,
- Haiyang