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转发：回复：Re: about ZoneHigh occupying ram from last address of below 4G ram
by penghao122＠sina.com 15 Apr '15

15 Apr '15

----- 原始邮件 ----- 发件人：<penghao122(a)sina.com> 收件人："Kevin O'Connor" <kevin(a)koconnor.net> 主题：回复：Re: [SeaBIOS] about ZoneHigh occupying ram from last address of below 4G ram 日期：2015年04月15日 21点15分 ----- 原始邮件 ----- 发件人：Kevin O'Connor <kevin(a)koconnor.net> 收件人：penghao122(a)sina.com 抄送人：seabios <seabios(a)seabios.org> 主题：Re: [SeaBIOS] about ZoneHigh occupying ram from last address of below 4G ram 日期：2015年04月15日 00点45分 On Tue, Apr 14, 2015 at 11:57:08PM +0800, penghao122(a)sina.com wrote: > I'm using seabios 1.7.5-0 for kvm ,and I find some problem when > using windows 7 64bit bandvirtual machine.If I configure the windows > 7 64bit vm memory to 8GB ,the vm can't boot up very often(some > win7-64bit version easy to trigger) .I use trace-cmd tool to trace > it ,the vm just scan from last ram of below 4G(0xc000_0000) to 4G > address byte by byte.This is very time-consuming.From E820 table,the > address range contain nothing(it is an address hole). > > I query clue from seabios because I can't find any problems in kvm > or qemu. seabios keep a range of ram from last address below 4G as > zonehigh ram .I guess the windows os see a not aligned ram address > space and scan from 0xc000_0000. so I try to change the ZoneHigh to > low address space (I choose 128MB,grub use from 1MB address > space).after I changed,I can boot win7-64bit vm normally. > > So I want to know whether changing ZoneHigh to 128MB can be a > general modification. I haven't seen any other reports of issues like this with Win7. I suspect something else is going on. Please provide the full debug log (as described at: http://seabios.org/Debugging ) with an unmodified seabios from both a succesful boot event and a failed boot event. -Kevin I just can' boot succesfully if I use unmodified seabios (vm using 8 GB memory).I will try again. The attachment is the output of seabios when booting failed.

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about ZoneHigh occupying ram from last address of below 4G ram
by penghao122＠sina.com 14 Apr '15

14 Apr '15

I'm using seabios 1.7.5-0 for kvm ,and I find some problem when using windows 7 64bit bandvirtual machine.If I configure the windows 7 64bit vm memory to 8GB ,the vm can't boot up very often(some win7-64bit version easy to trigger) .I use trace-cmd tool to trace it ,the vm just scan from last ram of below 4G(0xc000_0000) to 4G address byte by byte.This is very time-consuming.From E820 table,the address range contain nothing(it is an address hole). I query clue from seabios because I can't find any problems in kvm or qemu. seabios keep a range of ram from last address below 4G as zonehigh ram .I guess the windows os see a not aligned ram address space and scan from 0xc000_0000. so I try to change the ZoneHigh to low address space (I choose 128MB,grub use from 1MB address space).after I changed,I can boot win7-64bit vm normally. So I want to know whether changing ZoneHigh to 128MB can be a general modification.

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[PATCHv3 0/2] Emulate "leal" instruction to workaround x86emu bugs
by Kevin O'Connor 13 Apr '15

13 Apr '15

With a few additional checks it's possible to emulate all the leal cases without requiring a function call. Although this makes the vgafixup.py code a little more complex it eliminates the need for the "emulate_leal" function and it produces better code. In my tests, almost all "leal" instructions are replaced with 4 (or fewer) instructions. -Kevin Kevin O'Connor (2): vgabios: Add config option for assembler fixups vgabios: Emulate "leal" instruction Makefile | 21 +++++++++--------- scripts/vgafixup.py | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++--- vgasrc/Kconfig | 10 +++++++++ vgasrc/vgaentry.S | 28 +++++------------------ 4 files changed, 87 insertions(+), 36 deletions(-) -- 1.9.3

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[PATCH 0/3] Emulate "leal" instruction to workaround x86emu bugs
by Kevin O'Connor 11 Apr '15

11 Apr '15

This series extends the existing "vgafixup.py" assembler patching mechanism to also patch out the "leal" instruction that old versions of x86emu don't support. With this series in place, fc11 and fc12 can now boot into graphics when using qemu with "std" vga. Because the assembler munging is getting a bit complicated, the first patch adds a compile time option to disable all of it. This allows one to build the vgabios without any of the workarounds. The out-of-line emulate_leal function does have a bit of overhead - one x86 instruction is replaced with over 20 instructions. The last patch in the series optimizes the common case so that most leal instructions are replaced with only 4-6 instructions. Also at: https://github.com/KevinOConnor/seabios/tree/testing -Kevin Kevin O'Connor (3): vgabios: Add config option for assembler fixups vgabios: Emulate "leal" instruction vgabios: Optimize leal instruction fixup Makefile | 21 +++++++++--------- scripts/vgafixup.py | 62 ++++++++++++++++++++++++++++++++++++++++++++++++++--- vgasrc/Kconfig | 10 +++++++++ vgasrc/vgaentry.S | 49 +++++++++++++++++++++++------------------- 4 files changed, 107 insertions(+), 35 deletions(-) -- 1.9.3

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Re: [SeaBIOS] FreeBSD VESA console not working with SeaBIOS
by Kevin O'Connor 09 Apr '15

09 Apr '15

On Thu, Apr 09, 2015 at 11:32:25PM +0200, Jon Doe wrote: > On Thu, Apr 9, 2015 at 6:54 PM, Kevin O'Connor <kevin(a)koconnor.net> wrote: > > I gave it a shot anyway - seabios patch is below. [...] > > I can report that this patch also works for FreeBSD 8.2's VESA > console. There seems to be some unrelated problem when running > 1.8-stable so I applied it to rel-1.7.5.2 I'm not surprised seabios master would still have a problem (due to recently reported issue with smsww), but I am surprised 1.8-stable would have a problem. Can you confirm it was 1.8-stable that was still broken with the patch? -Kevin

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[PATCH] smbios: Use integer signature instead of string signature
by Kevin O'Connor 09 Apr '15

09 Apr '15

Change the smbios structure to use a 4 byte u32 signature field instead of a 4 byte character string field. In practice, this allows the compiler to place the signature in the initialize code segment and thus makes it less likely the signature would be found in the f-segment. (If the smbios signature is found in the f-segment it can confuse some table scans.) Signed-off-by: Kevin O'Connor <kevin(a)koconnor.net> --- src/fw/biostables.c | 2 +- src/fw/smbios.c | 2 +- src/std/smbios.h | 4 +++- 3 files changed, 5 insertions(+), 3 deletions(-) diff --git a/src/fw/biostables.c b/src/fw/biostables.c index 50a891b..450aca2 100644 --- a/src/fw/biostables.c +++ b/src/fw/biostables.c @@ -271,7 +271,7 @@ copy_smbios(void *pos) if (SMBiosAddr) return; struct smbios_entry_point *p = pos; - if (memcmp(p->anchor_string, "_SM_", 4)) + if (p->signature != SMBIOS_SIGNATURE) return; if (checksum(pos, 0x10) != 0) return; diff --git a/src/fw/smbios.c b/src/fw/smbios.c index dba0541..f3b5ad9 100644 --- a/src/fw/smbios.c +++ b/src/fw/smbios.c @@ -37,7 +37,7 @@ smbios_entry_point_setup(u16 max_structure_size, struct smbios_entry_point ep; memset(&ep, 0, sizeof(ep)); - memcpy(ep.anchor_string, "_SM_", 4); + ep.signature = SMBIOS_SIGNATURE; ep.length = 0x1f; ep.smbios_major_version = 2; ep.smbios_minor_version = 4; diff --git a/src/std/smbios.h b/src/std/smbios.h index 0513716..4ccf2ea 100644 --- a/src/std/smbios.h +++ b/src/std/smbios.h @@ -3,11 +3,13 @@ #include "types.h" // u32 +#define SMBIOS_SIGNATURE 0x5f4d535f // "_SM_" + /* SMBIOS entry point -- must be written to a 16-bit aligned address between 0xf0000 and 0xfffff. */ struct smbios_entry_point { - char anchor_string[4]; + u32 signature; u8 checksum; u8 length; u8 smbios_major_version; -- 1.9.3

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Re: [SeaBIOS] FreeBSD VESA console not working with SeaBIOS
by Kevin O'Connor 09 Apr '15

09 Apr '15

On Mon, Apr 06, 2015 at 10:05:36AM +0200, Jon Doe wrote: > Here's a log showing a boot into X, then switching to console, then > trying to kldload vesa.ko. Looks like X is happily probing vbe modes, > but the console chokes with "SeaVGABIOS: x86emu leal trap!". That error message indicates that the vga bios is running in an older version of the x86emu emulator that is too broken to be capable of running the vga bios. (Specifically, the "leal" instruction is not properly implemented.) Unfortunately, there isn't much that can be done about this on the vga bios side. There are newer versions of x86emu available that are capable of emulating SeaVGABIOS, but I don't know if someone has already integrated it into FreeBSD or how one would go about integrating it. Alternatively, since the log shows the vesa mode scan was run natively instead of via x86emu, it may be possible to change the code to switch modes using native execution instead of via x86emu. -Kevin

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[PATCH] vgabios: Don't use "smsww" instruction - it confuses x86emu
by Kevin O'Connor 09 Apr '15

09 Apr '15

Commit 251e2638 introduced the "smsww" instruction to the vgabios. Unfortunately, it appears at least some versions of x86emu crash when executing that instruction (eg, FC13 installer crashes). That instruction wasn't required to work around the problem fixed in 251e2638, so just avoid it. Signed-off-by: Kevin O'Connor <kevin(a)koconnor.net> --- The fix for the "skifree bug" tickled yet another old OS problem - old versions of x86emu don't like smsww. :-( The smsww wasn't strickly necessary, so this patch just stops using it. --- vgasrc/vgabios.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/vgasrc/vgabios.c b/vgasrc/vgabios.c index 7c1f0b8..f07e85b 100644 --- a/vgasrc/vgabios.c +++ b/vgasrc/vgabios.c @@ -304,7 +304,7 @@ vga_set_mode(int mode, int flags) SET_BDA(video_mode, 0xff); SET_BDA_EXT(vbe_mode, mode | (flags & MF_VBEFLAGS)); SET_BDA_EXT(vgamode_offset, (u32)vmode_g); - if (CONFIG_VGA_ALLOCATE_EXTRA_STACK && !(getcr0_vm86() & CR0_PE)) + if (CONFIG_VGA_ALLOCATE_EXTRA_STACK) // Disable extra stack if it appears a modern OS is in use. // This works around bugs in some versions of Windows (Vista // and possibly later) when the stack is in the e-segment. -- 1.9.3

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Re: [SeaBIOS] FreeBSD VESA console not working with SeaBIOS
by Kevin O'Connor 09 Apr '15

09 Apr '15

On Thu, Apr 09, 2015 at 10:59:11AM +0200, Jon Doe wrote: > On Thu, Apr 9, 2015 at 4:32 AM, Kevin O'Connor <kevin(a)koconnor.net> wrote: > > On Wed, Apr 08, 2015 at 08:48:11PM +0200, Peter Stuge wrote: > >> Kevin O'Connor wrote: > >> > (Specifically, the "leal" instruction is not properly implemented.) > >> > > >> > Unfortunately, there isn't much that can be done about this on the vga > >> > bios side. > >> > >> Really? Impossible to save flags, use other opcodes, and restore flags? > >> > >> lea isn't used in vgasrc/ besides in the trap that triggers the fault. > >> > >> In src/romlayout.S lea is used in two places to bump esp before calls. > >> If those code paths are used also by SeaVGABIOS then maybe they could > >> be rewritten with simpler instructions? > > > > The problem is not with leal in hand written assembler - the problem > > is with leal instructions generated by gcc. To see the assembler gcc > > produces for the vgabios one can look at out/vgaccode16.raw.s . Or, > > alternatively, one can run: > > objdump -m i386 -M i8086 -M suffix -ldr out/vgarom.o > > > > We've fixed up gcc assembler in the past (see scripts/vgafixup.py) to > > work around x86emu. However, the leal instruction seems painful to > > patch out - particularly so when %esp is one of the registers read or > > written in the leal instruction. If anyone wants to take a stab > > at a workaround, feel free to submit a patch. > > > > -Kevin > > Might be instructive to look at how vmware and virtualbox BIOSes is > able to work around this problem. Surely their BIOS code is written in > C? My understanding is that traditional proprietary BIOS and VGABIOS are written in assembler. There are 16bit C compilers that (almost assuredly) wont generate 32bit instructions such as leal - for example, openwatcom and bcc. However, using them results in other problems. > Fixing this in x86emu is probably the right thing to do (just checked, > PCBSD 10.1's x86emu is still broken), but this won't help if you're > stuck with an old release. It's also possible to use the older "lgpl vgabios" - http://www.nongnu.org/vgabios/ - it is written in assembler and C code (that is compiled with bcc). -Kevin

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Re: [SeaBIOS] FreeBSD VESA console not working with SeaBIOS
by Paolo Bonzini 09 Apr '15

09 Apr '15

On 09/04/2015 10:59, Jon Doe wrote: > Might be instructive to look at how vmware and virtualbox BIOSes is > able to work around this problem. Surely their BIOS code is written in > C? At least Bochs's vgabios was written to run exclusively in 16-bit mode, using not just a different compiler than gcc but effectively another instruction set (16-bit x86 instructions and especially 16-bit addressing modes are almost never used in 32-bit mode). Paolo

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