> -----Original Message----- > From: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> > Sent: 9 February, 2023 5:44 PM > To: JiaJie Ho <jiajie.ho@xxxxxxxxxxxxxxxx> > Cc: David S . Miller <davem@xxxxxxxxxxxxx>; Rob Herring > <robh+dt@xxxxxxxxxx>; Krzysztof Kozlowski > <krzysztof.kozlowski+dt@xxxxxxxxxx>; Emil Renner Berthing > <kernel@xxxxxxxx>; Conor Dooley <conor.dooley@xxxxxxxxxxxxx>; linux- > crypto@xxxxxxxxxxxxxxx; devicetree@xxxxxxxxxxxxxxx; linux- > kernel@xxxxxxxxxxxxxxx; linux-riscv@xxxxxxxxxxxxxxxxxxx > Subject: Re: [PATCH v2 4/4] crypto: starfive - Add hash and HMAC support > > On Thu, Feb 09, 2023 at 09:33:06AM +0000, JiaJie Ho wrote: > > > > The DMA can only support 32-bit addressing. > > So, I am copying everything in case kernel allocated memory region >32-bit > for a user app. > > Does your hardware support scatter-and-gather? If so you should at least > allocate individual pages rather than one contiguous buffer. > > Then you can allocate them on-demand rather than before-hand. > > It would also be nice to not do the copy if the input you were given was in > low memory (and contiguous if your hardware doesn't do SG). > I'll try this then. Thanks, Jia Jie
