From mboxrd@z Thu Jan  1 00:00:00 1970
Subject: Re: [edk2-devel] static data in dxe_runtime modules
To: Roman Kagan <rkagan@virtuozzo.com>,devel@edk2.groups.io
From: "Andrew Fish" <afish@apple.com>
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Date: Fri, 02 Aug 2019 16:54:35 -0700
References: <20190801191621.GB14235@rkaganb.sw.ru>
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Roman,

Sorry for the top post, as my email client seems to have eating your email=
.

1) In C static scopes the visibility of the symbol from a compiler linker =
point of view, but the static and non-static globals are going to be stored=
 in the same section of the image. On macOS clang the only difference is th=
e static global does not also have a .globl assembly directive to make the =
label visible outside the scope of the module.

In general Runtime Drivers will gather data that is only available at boot=
 time and store this data in globals, so you can't clear out part of the im=
age on fix-up as that would break a lot of other stuff.

2) The corrrect answer would be to fixup any pointers needed at runtime vi=
a RuntimeCryptLibAddressChangeEvent(). On option would be to have an array =
of the addresses of the static variables and have RuntimeCryptLibAddressCha=
ngeEvent() walk that and fixup the Physical addresses to virtual addresses =
by calling EfiConvertPointer().

Thanks,

Andrew Fish

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Roman,<br /><br />Sorry for the top post, as my email client seems to have =
eating your email.<br /><br />1) In C static scopes the visibility of the s=
ymbol from a compiler linker point of view, but the static and non-static g=
lobals are going to be stored in the same section of the image. On macOS cl=
ang the only difference is the static global does not also have a .globl as=
sembly directive to make the label visible outside the scope of the module.=
&nbsp;<br /><br />In general Runtime Drivers will gather data that is only =
available at boot time and store this data in globals, so you can't clear o=
ut part of the image on fix-up as that would break a lot of other stuff.&nb=
sp;<br /><br />2) The corrrect answer would be to fixup any pointers needed=
 at runtime via&nbsp;<span style=3D"white-space: pre-wrap;">RuntimeCryptLib=
AddressChangeEvent(). On option would be to have an array of the addresses =
of the static variables and have </span><span style=3D"white-space: pre-wra=
p;">RuntimeCryptLibAddressChangeEvent() walk that and fixup the Physical ad=
dresses to virtual addresses by calling </span>EfiConvertPointer().<br /><b=
r />Thanks,<br /><br />Andrew Fish

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