> On 20 May 2019, at 5:28, Kevin O'Connor <ke...@koconnor.net> wrote: > > On Fri, May 17, 2019 at 11:57:23PM +0300, Sam Eiderman wrote: >> From: Liran Alon <liran.a...@oracle.com> >> >> Windows kernel extracts various BIOS information at boot-time. >> The method it uses to extract SystemBiosDate is very hueristic. >> It is done by nt!CmpGetBiosDate(). >> >> nt!CmpGetBiosDate() works by scanning all BIOS memory from 0xF0000 to >> 0xFFFF5 (FSEG) in search for a string which is formatted like a date. >> It then chooses the string which represents the most recent date, and >> writes it to: >> >> HKLM/HARDWARE/DESCRIPTION/System SystemBiosDate >> >> This date should usually be BiosDate located at FSEG(0xFFF5). > > FWIW, if you want to ensure a stable date is found, it's probably > simpler to force a valid date string to be present in the f-segment. > Something like: char win_bios_date[] VARFSEG = " 04/01/2014 "; > > As with my previous emails, I'd recommend using a hard-coded date (not > a build date) - as this tends to improve reproducibility.
The thing is, if the date reported by smbios tables is 05/02/2015 (which is bigger than 04/01/2014) so: If smbios tables are in fseg - Windows will select the most recent date - 05/02/2015 If not - Windows will select the most recent date (the only one it found) - 04/01/2014 So 'char win_bios_date[] VARFSEG = " 04/01/2014 “‘ will not help. Sam > > -Kevin
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