H. Peter Anvin wrote:
I just got the following message on the syslinux mailing list:
2. On some platforms (vmware for example :), READING from the video memory
in the 32bit mode is impossible (causes an exeption). Taking in to account
that the scroll function in ilinux/arch/i386/boot/compressed/misc.c
works using a memcpy of the video memory, when the linux bootsector is given
control and the cursor is at the end of the screen (-1-2 lines) an exception is
arisen and in the presence of it's handler in the bootloader the system halts.
Both lilo and grub handle this situation - the cursor is always somewhere at the
middle of the screen when the control is given to the linux bootsector.
When using pxelinux taking in to account that the PXE bios prints out the
presence of the second initramfs which causes the screen to scroll and the bug
to appear :)
A very simple solution - the screen is cleared before giving control to the
linux bootsector (in the patch).
First of all, is this actually true? This seems like a monumental screwup.
Yes. Is this a report of observed failure? And how would VMWare even
go about implementing this kind of misfeature? Maybe it fails with
particular instructions reading the framebuffer?
Second, assuming it is true, what should be done about it? The notion
that the bootloader should erase the screen is ridiculous since we spend
a lot of effort maintaining the screen context from 16-bit code.
I see a couple of options:
Maintain a shadow framebuffer, and copy it to the real framebuffer on
update...
J
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