Re: Supporting new interfaces in phosphor-ipmi-flash

[Troy Lee <troy_lee@aspeedtech.com>]

Hi Andrew,

The 01/28/2021 07:14, Andrew Jeffery wrote:
> 
> 
> On Wed, 27 Jan 2021, at 20:13, Troy Lee wrote:
> > Hi team,
> > 
> > For security consideration, user might want to disable AST2500/AST2600 
> > P2A functionality by default. To compensate the effect to 
> > phosphor-ipmi-flash, we're planning to support two alternative in-band 
> > firmware upgrade over PCIe for AST2500/AST2600 (AST2520 and AST2620 are 
> > excluded):
> >  - Through a reserved **VGA** memory on BAR[0], or
> >  - Through a reserved **PCIe** shared memory on BAR[1]
> > 
> > The usage pretty much the same as P2A, but it runs on different BAR, 
> > offset and length.
> > This will involves modifying phosphor-ipmi-flash/[tools|bmc]. Should I 
> > create new **interfaces**, e.g. astpcie/astvga?
> > 
> 
> This is the HOST2BMC functionality in the 2600 datasheet?
> 
> It would be great to have more detail on how it works.
> 
> Andrew

No, it doesn't use HOST2BMC interface, it uses VGA controller's mmio.
Perhaps HOST2BMC is also a possible solution, too.

02:00.0 0300: 1a03:2000 (rev 51) (prog-if 00 [VGA controller])
        Subsystem: 1a03:2000
        Flags: bus master, medium devsel, latency 0, IRQ 16
        Memory at f6000000 (32-bit, non-prefetchable) [size=16M]  <--- Option 1
        Memory at f7040000 (32-bit, non-prefetchable) [size=128K] <--- Option 2
        I/O ports at e000 [size=128]
        Expansion ROM at 000c0000 [disabled] [size=128K]
        Capabilities: [40] Power Management version 3
        Capabilities: [50] MSI: Enable- Count=1/4 Maskable- 64bit+
        Kernel driver in use: ast
        Kernel modules: ast

Option 1 allocates a 1MB memory from the end of VGA memory, so it will
need some change to VBIOS.

Option 2 allocates a 4K memory from BMC memory space. Since the buffer
is smaller, the ipmi-blob protocol overhead will be greater.


Thanks,
Troy Lee