Date: Thu, 23 Jan 2003 14:57:45 -0800 From: Marcel Moolenaar <marcel@xcllnt.net> To: Nicolas Souchu <nsouch@free.fr> Cc: arch@FreeBSD.ORG, Rodolphe Ortalo <ortalo@laas.fr> Subject: Re: the mythical syscons redesign document ( was Re: Porting wscons ) Message-ID: <20030123225745.GB5741@dhcp01.pn.xcllnt.net> In-Reply-To: <20030123232923.E12164@armor.fastether> References: <20030122010246.52789.qmail@web13404.mail.yahoo.com> <1043236066.28124.6.camel@builder02.qubesoft.com> <20030122223626.B8449@armor.fastether> <20030122220029.GD590@dhcp01.pn.xcllnt.net> <20030123075556.A10370@armor.fastether> <20030123071232.GA80532@dhcp01.pn.xcllnt.net> <20030123232923.E12164@armor.fastether>
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On Thu, Jan 23, 2003 at 11:29:23PM +0100, Nicolas Souchu wrote: > On Wed, Jan 22, 2003 at 11:12:32PM -0800, Marcel Moolenaar wrote: > > > I agree. But booting a true PCI/AGP (and not ISA) graphic card without > > > the bus stuff initialized seems very hard. > > > > Yes and no. The PCI standard has defined the legacy memory address of > > the frame buffer and the legacy I/O port range for compatibility. I > > expect that we can safely probe that. I don't know how this works in > > non-PCI system though... > > But would you find the same HW on totally different bus architectures? The > same graphic chipset that would work with ISA and PCI? No. Not necessarily in the same way. This makes early console probing a platform dependent operation. On PCs or PCI-based systems, you should be able to test for the presence of VGA that way. On non- PCI non-PC systems (that possibly also don't use VGA by default), other methods have to be found/implemented. > Thus the bus has not to be > too abstracted. I think one should abstract the graphic chipset from > *its* bus (PCI in many cases) and that's all. The MI code should have complete bus-abstraction by default. MD code should be used when platform-specific knowledge has to be used. > As you say, PCI standard has defined... and I think this definition can be > implemented much more simply than FreeBSD does, at least for booting a > console. On i386, yes. Note that even though i386 and ia64 have VGA by default now, already new (is it new?) graphics standards are being created. For example the Universal Graphics Adapter (UGA): http://www.microsoft.com/hwdev/tech/display/uga/default.asp I'm not saying that UGA is the light we've been searching for all these years, but the signal is clear: We should not assume a single graphics standard, like VGA, if we want to rework our console. > This simple code could be written for different architectures to > init the same driver on any arch/OS before the rest of the OS bus > abstraction. Roughly, yes. It may not be trivial in all cases, but this is what it boils down to. -- Marcel Moolenaar USPA: A-39004 marcel@xcllnt.net To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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