On Wed, May 30, 2018 at 2:07 AM, Udit Kumar udit.kumar@nxp.com wrote:
-----Original Message----- From: Rob Herring [mailto:robherring2@gmail.com] Sent: Tuesday, May 29, 2018 8:32 PM To: Udit Kumar udit.kumar@nxp.com Cc: Architecture Mailman List boot-architecture@lists.linaro.org; nd@arm.com; arm.ebbr-discuss@arm.com Subject: Re: Issue#9 Document hardware need (if any)
On Fri, May 25, 2018 at 8:47 PM, Udit Kumar udit.kumar@nxp.com wrote:
-----Original Message----- From: Rob Herring [mailto:robherring2@gmail.com] Sent: Friday, May 25, 2018 8:18 PM To: Udit Kumar udit.kumar@nxp.com Cc: Architecture Mailman List boot-architecture@lists.linaro.org; nd@arm.com; arm.ebbr-discuss@arm.com Subject: Re: Issue#9 Document hardware need (if any)
On Fri, May 25, 2018 at 1:44 AM, Udit Kumar udit.kumar@nxp.com wrote:
Hi At present, I don't see any specific hardware requirement for EBBR except
ARMv8 CPU. Current document covers it very well.
You have to have block storage. Perhaps UEFI implies that. Boards like the CHIP only have raw NAND and a USB connector by default. So is USB
MS enough?
Yes but such need is not must to have EBBR running.
I don't follow.
I meant, what hardware features a SOC must have to run EBBR. This include IPs/CPU architecture etc. NAND/USB could be optional, this is not must for EBBR.
EBBR is about what the distros need/want. Raw NAND is never going to be supported by distros (in their installers, you can always manually craft images for NAND). USB is maybe too specific (though SD card is really the only other choice), but there needs to be either some removable media or network boot (or perhaps we can say both) for an OS installer and then there must be a block device to install to. That's one usecase. The 2nd is that you create an OS image offline and put the image on either a USB MS device or SD card. So that is just a subset of the first (unless the first only supports net boot).
I think being explicit with h/w requirements implied by UEFI would be a good thing. If I'm designing a board, I don't want to have to sort thru UEFI specs to distill down a bullet list of h/w reqs.
I like to cover here, all on/off chip components could be IP/peripherals needed
for EBBR.
Like if USB is present, minimum version of xchi or echi needs to be supported
by hardware.
One look at XHCI or EHCI drivers and the variations across SoCs will tell you that just specifying those specs is pointless. But it is probably worth saying something about USB. Perhaps saying USB host port(s) (more than 1?) required and the firmware must support booting from USB.
I put USB as an example. Please refer SBSA, which mandate the version of ECHI/XCHI
As Grant said, SBSA has a different focus. IMO, it has the same issue I mentioned though. Just look at the mess the SBSA uart is.
should be supported. Also this specify other IPs too like Timer, UART, GiC etc
IMO, such strict hardware requirement for EBBR will not be useful.
Agreed. We'd be kidding ourselves that we have any say in the SoC design.
Rob