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Re: [PATCH 0/3] Remove deprecated pc-0.x machine types and related hacks

From: Gerd Hoffmann
Subject: Re: [PATCH 0/3] Remove deprecated pc-0.x machine types and related hacks
Date: Fri, 6 Dec 2019 11:57:41 +0100

> > $ git-grep pc-0
> > hw/display/vga-pci.c:        /* compatibility with pc-0.13 and older */
> > hw/display/vga.c:    /* With pc-0.12 and below we map both the PCI BAR and 
> > the fixed VBE region,
> > hw/display/vmware_vga.c:        /* compatibility with pc-0.13 and older */
> These are the "rombar" hacks that I've mentioned above. The question is
> whether we want to remove them or whether I should just adjust the comments?

Hmm.  All that cruft ...

vga maps the framebuffer @ 0xe0000000 with rombar=off. It's an alias of
the pci memory bar.  rombar=off is basically a flag for "really old
firmware" here, vgabios used to have that address hardcoded, a decade
ago.  We fixed that roughly the same timeframe where we switched to
seabios, which in turn allowed us to place the vgabios in the pci rom
bar (instead of copying it to 0xa000 in guest ram).  Which is probably
the reason why we have only one switch for both.

I don't expect anyone actually sets the rombar property for vga devices
(it's more common for NICs, for network boot tweaks), so I guess we can
get away with simply dropping the hacks in vga-pci.c and vmware_vga.c.
The comment in vga.c is not fully correct though, isa-vga needs that
too, so we have to keep vga_init_vbe for the time being ...


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