Re: SSE in kernel?

2020-06-23 Thread Philip Guenther
On Mon, Jun 22, 2020 at 9:12 PM wrote: > Are SSE instructions allowed in the AMD64 kernel? Is #ifdef __SSE__ > a sufficient guard? > > I have a rasops32 putchar with SSE that is 2x faster. > As Bryan and Patrick noted: it's possible, but there are restrictions and costs. The main restriction

Re: SSE in kernel?

2020-06-23 Thread Bryan Steele
On Tue, Jun 23, 2020 at 01:03:18PM +0200, Patrick Wildt wrote: > On Tue, Jun 23, 2020 at 06:51:20AM -0400, Bryan Steele wrote: > > On Mon, Jun 22, 2020 at 11:10:10PM -0700, jo...@armadilloaerospace.com > > wrote: > > > Are SSE instructions allowed in the AMD64 kernel? Is #ifdef __SSE__ > > > a

Re: SSE in kernel?

2020-06-23 Thread Bryan Steele
On Tue, Jun 23, 2020 at 06:51:22AM -0400, Bryan Steele wrote: > On Mon, Jun 22, 2020 at 11:10:10PM -0700, jo...@armadilloaerospace.com wrote: > > Are SSE instructions allowed in the AMD64 kernel? Is #ifdef __SSE__ > > a sufficient guard? > > > > I have a rasops32 putchar with SSE that is 2x

Re: SSE in kernel?

2020-06-23 Thread Patrick Wildt
On Tue, Jun 23, 2020 at 06:51:20AM -0400, Bryan Steele wrote: > On Mon, Jun 22, 2020 at 11:10:10PM -0700, jo...@armadilloaerospace.com wrote: > > Are SSE instructions allowed in the AMD64 kernel? Is #ifdef __SSE__ > > a sufficient guard? > > > > I have a rasops32 putchar with SSE that is 2x

Re: SSE in kernel?

2020-06-23 Thread Bryan Steele
On Mon, Jun 22, 2020 at 11:10:10PM -0700, jo...@armadilloaerospace.com wrote: > Are SSE instructions allowed in the AMD64 kernel? Is #ifdef __SSE__ > a sufficient guard? > > I have a rasops32 putchar with SSE that is 2x faster. No, in general you cannot using FP instructions in the kernel, also

SSE in kernel?

2020-06-23 Thread johnc
Are SSE instructions allowed in the AMD64 kernel? Is #ifdef __SSE__ a sufficient guard? I have a rasops32 putchar with SSE that is 2x faster.